api, login, auth

1 files changed, 2178 insertions, 0 deletions

diff --git a/node_modules/mongodb/lib/collection.js b/node_modules/mongodb/lib/collection.js
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+'use strict';
+
+const deprecate = require('util').deprecate;
+const deprecateOptions = require('./utils').deprecateOptions;
+const checkCollectionName = require('./utils').checkCollectionName;
+const ObjectID = require('./core').BSON.ObjectID;
+const MongoError = require('./core').MongoError;
+const normalizeHintField = require('./utils').normalizeHintField;
+const decorateCommand = require('./utils').decorateCommand;
+const decorateWithCollation = require('./utils').decorateWithCollation;
+const decorateWithReadConcern = require('./utils').decorateWithReadConcern;
+const formattedOrderClause = require('./utils').formattedOrderClause;
+const ReadPreference = require('./core').ReadPreference;
+const unordered = require('./bulk/unordered');
+const ordered = require('./bulk/ordered');
+const ChangeStream = require('./change_stream');
+const executeLegacyOperation = require('./utils').executeLegacyOperation;
+const WriteConcern = require('./write_concern');
+const ReadConcern = require('./read_concern');
+const MongoDBNamespace = require('./utils').MongoDBNamespace;
+const AggregationCursor = require('./aggregation_cursor');
+const CommandCursor = require('./command_cursor');
+
+// Operations
+const ensureIndex = require('./operations/collection_ops').ensureIndex;
+const group = require('./operations/collection_ops').group;
+const parallelCollectionScan = require('./operations/collection_ops').parallelCollectionScan;
+const removeDocuments = require('./operations/common_functions').removeDocuments;
+const save = require('./operations/collection_ops').save;
+const updateDocuments = require('./operations/common_functions').updateDocuments;
+
+const AggregateOperation = require('./operations/aggregate');
+const BulkWriteOperation = require('./operations/bulk_write');
+const CountDocumentsOperation = require('./operations/count_documents');
+const CreateIndexesOperation = require('./operations/create_indexes');
+const DeleteManyOperation = require('./operations/delete_many');
+const DeleteOneOperation = require('./operations/delete_one');
+const DistinctOperation = require('./operations/distinct');
+const DropCollectionOperation = require('./operations/drop').DropCollectionOperation;
+const DropIndexOperation = require('./operations/drop_index');
+const DropIndexesOperation = require('./operations/drop_indexes');
+const EstimatedDocumentCountOperation = require('./operations/estimated_document_count');
+const FindOperation = require('./operations/find');
+const FindOneOperation = require('./operations/find_one');
+const FindAndModifyOperation = require('./operations/find_and_modify');
+const FindOneAndDeleteOperation = require('./operations/find_one_and_delete');
+const FindOneAndReplaceOperation = require('./operations/find_one_and_replace');
+const FindOneAndUpdateOperation = require('./operations/find_one_and_update');
+const GeoHaystackSearchOperation = require('./operations/geo_haystack_search');
+const IndexesOperation = require('./operations/indexes');
+const IndexExistsOperation = require('./operations/index_exists');
+const IndexInformationOperation = require('./operations/index_information');
+const InsertManyOperation = require('./operations/insert_many');
+const InsertOneOperation = require('./operations/insert_one');
+const IsCappedOperation = require('./operations/is_capped');
+const ListIndexesOperation = require('./operations/list_indexes');
+const MapReduceOperation = require('./operations/map_reduce');
+const OptionsOperation = require('./operations/options_operation');
+const RenameOperation = require('./operations/rename');
+const ReIndexOperation = require('./operations/re_index');
+const ReplaceOneOperation = require('./operations/replace_one');
+const StatsOperation = require('./operations/stats');
+const UpdateManyOperation = require('./operations/update_many');
+const UpdateOneOperation = require('./operations/update_one');
+
+const executeOperation = require('./operations/execute_operation');
+
+/**
+ * @fileOverview The **Collection** class is an internal class that embodies a MongoDB collection
+ * allowing for insert/update/remove/find and other command operation on that MongoDB collection.
+ *
+ * **COLLECTION Cannot directly be instantiated**
+ * @example
+ * const MongoClient = require('mongodb').MongoClient;
+ * const test = require('assert');
+ * // Connection url
+ * const url = 'mongodb://localhost:27017';
+ * // Database Name
+ * const dbName = 'test';
+ * // Connect using MongoClient
+ * MongoClient.connect(url, function(err, client) {
+ *   // Create a collection we want to drop later
+ *   const col = client.db(dbName).collection('createIndexExample1');
+ *   // Show that duplicate records got dropped
+ *   col.find({}).toArray(function(err, items) {
+ *     test.equal(null, err);
+ *     test.equal(4, items.length);
+ *     client.close();
+ *   });
+ * });
+ */
+
+const mergeKeys = ['ignoreUndefined'];
+
+/**
+ * Create a new Collection instance (INTERNAL TYPE, do not instantiate directly)
+ * @class
+ */
+function Collection(db, topology, dbName, name, pkFactory, options) {
+  checkCollectionName(name);
+
+  // Unpack variables
+  const internalHint = null;
+  const slaveOk = options == null || options.slaveOk == null ? db.slaveOk : options.slaveOk;
+  const serializeFunctions =
+    options == null || options.serializeFunctions == null
+      ? db.s.options.serializeFunctions
+      : options.serializeFunctions;
+  const raw = options == null || options.raw == null ? db.s.options.raw : options.raw;
+  const promoteLongs =
+    options == null || options.promoteLongs == null
+      ? db.s.options.promoteLongs
+      : options.promoteLongs;
+  const promoteValues =
+    options == null || options.promoteValues == null
+      ? db.s.options.promoteValues
+      : options.promoteValues;
+  const promoteBuffers =
+    options == null || options.promoteBuffers == null
+      ? db.s.options.promoteBuffers
+      : options.promoteBuffers;
+  const collectionHint = null;
+
+  const namespace = new MongoDBNamespace(dbName, name);
+
+  // Get the promiseLibrary
+  const promiseLibrary = options.promiseLibrary || Promise;
+
+  // Set custom primary key factory if provided
+  pkFactory = pkFactory == null ? ObjectID : pkFactory;
+
+  // Internal state
+  this.s = {
+    // Set custom primary key factory if provided
+    pkFactory: pkFactory,
+    // Db
+    db: db,
+    // Topology
+    topology: topology,
+    // Options
+    options: options,
+    // Namespace
+    namespace: namespace,
+    // Read preference
+    readPreference: ReadPreference.fromOptions(options),
+    // SlaveOK
+    slaveOk: slaveOk,
+    // Serialize functions
+    serializeFunctions: serializeFunctions,
+    // Raw
+    raw: raw,
+    // promoteLongs
+    promoteLongs: promoteLongs,
+    // promoteValues
+    promoteValues: promoteValues,
+    // promoteBuffers
+    promoteBuffers: promoteBuffers,
+    // internalHint
+    internalHint: internalHint,
+    // collectionHint
+    collectionHint: collectionHint,
+    // Promise library
+    promiseLibrary: promiseLibrary,
+    // Read Concern
+    readConcern: ReadConcern.fromOptions(options),
+    // Write Concern
+    writeConcern: WriteConcern.fromOptions(options)
+  };
+}
+
+/**
+ * The name of the database this collection belongs to
+ * @member {string} dbName
+ * @memberof Collection#
+ * @readonly
+ */
+Object.defineProperty(Collection.prototype, 'dbName', {
+  enumerable: true,
+  get: function() {
+    return this.s.namespace.db;
+  }
+});
+
+/**
+ * The name of this collection
+ * @member {string} collectionName
+ * @memberof Collection#
+ * @readonly
+ */
+Object.defineProperty(Collection.prototype, 'collectionName', {
+  enumerable: true,
+  get: function() {
+    return this.s.namespace.collection;
+  }
+});
+
+/**
+ * The namespace of this collection, in the format `${this.dbName}.${this.collectionName}`
+ * @member {string} namespace
+ * @memberof Collection#
+ * @readonly
+ */
+Object.defineProperty(Collection.prototype, 'namespace', {
+  enumerable: true,
+  get: function() {
+    return this.s.namespace.toString();
+  }
+});
+
+/**
+ * The current readConcern of the collection. If not explicitly defined for
+ * this collection, will be inherited from the parent DB
+ * @member {ReadConcern} [readConcern]
+ * @memberof Collection#
+ * @readonly
+ */
+Object.defineProperty(Collection.prototype, 'readConcern', {
+  enumerable: true,
+  get: function() {
+    if (this.s.readConcern == null) {
+      return this.s.db.readConcern;
+    }
+    return this.s.readConcern;
+  }
+});
+
+/**
+ * The current readPreference of the collection. If not explicitly defined for
+ * this collection, will be inherited from the parent DB
+ * @member {ReadPreference} [readPreference]
+ * @memberof Collection#
+ * @readonly
+ */
+Object.defineProperty(Collection.prototype, 'readPreference', {
+  enumerable: true,
+  get: function() {
+    if (this.s.readPreference == null) {
+      return this.s.db.readPreference;
+    }
+
+    return this.s.readPreference;
+  }
+});
+
+/**
+ * The current writeConcern of the collection. If not explicitly defined for
+ * this collection, will be inherited from the parent DB
+ * @member {WriteConcern} [writeConcern]
+ * @memberof Collection#
+ * @readonly
+ */
+Object.defineProperty(Collection.prototype, 'writeConcern', {
+  enumerable: true,
+  get: function() {
+    if (this.s.writeConcern == null) {
+      return this.s.db.writeConcern;
+    }
+    return this.s.writeConcern;
+  }
+});
+
+/**
+ * The current index hint for the collection
+ * @member {object} [hint]
+ * @memberof Collection#
+ */
+Object.defineProperty(Collection.prototype, 'hint', {
+  enumerable: true,
+  get: function() {
+    return this.s.collectionHint;
+  },
+  set: function(v) {
+    this.s.collectionHint = normalizeHintField(v);
+  }
+});
+
+const DEPRECATED_FIND_OPTIONS = ['maxScan', 'fields', 'snapshot', 'oplogReplay'];
+
+/**
+ * Creates a cursor for a query that can be used to iterate over results from MongoDB
+ * @method
+ * @param {object} [query={}] The cursor query object.
+ * @param {object} [options] Optional settings.
+ * @param {number} [options.limit=0] Sets the limit of documents returned in the query.
+ * @param {(array|object)} [options.sort] Set to sort the documents coming back from the query. Array of indexes, [['a', 1]] etc.
+ * @param {object} [options.projection] The fields to return in the query. Object of fields to either include or exclude (one of, not both), {'a':1, 'b': 1} **or** {'a': 0, 'b': 0}
+ * @param {object} [options.fields] **Deprecated** Use `options.projection` instead
+ * @param {number} [options.skip=0] Set to skip N documents ahead in your query (useful for pagination).
+ * @param {Object} [options.hint] Tell the query to use specific indexes in the query. Object of indexes to use, {'_id':1}
+ * @param {boolean} [options.explain=false] Explain the query instead of returning the data.
+ * @param {boolean} [options.snapshot=false] DEPRECATED: Snapshot query.
+ * @param {boolean} [options.timeout=false] Specify if the cursor can timeout.
+ * @param {boolean} [options.tailable=false] Specify if the cursor is tailable.
+ * @param {boolean} [options.awaitData=false] Specify if the cursor is a a tailable-await cursor. Requires `tailable` to be true
+ * @param {number} [options.batchSize=1000] Set the batchSize for the getMoreCommand when iterating over the query results.
+ * @param {boolean} [options.returnKey=false] Only return the index key.
+ * @param {number} [options.maxScan] DEPRECATED: Limit the number of items to scan.
+ * @param {number} [options.min] Set index bounds.
+ * @param {number} [options.max] Set index bounds.
+ * @param {boolean} [options.showDiskLoc=false] Show disk location of results.
+ * @param {string} [options.comment] You can put a $comment field on a query to make looking in the profiler logs simpler.
+ * @param {boolean} [options.raw=false] Return document results as raw BSON buffers.
+ * @param {boolean} [options.promoteLongs=true] Promotes Long values to number if they fit inside the 53 bits resolution.
+ * @param {boolean} [options.promoteValues=true] Promotes BSON values to native types where possible, set to false to only receive wrapper types.
+ * @param {boolean} [options.promoteBuffers=false] Promotes Binary BSON values to native Node Buffers.
+ * @param {(ReadPreference|string)} [options.readPreference] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
+ * @param {boolean} [options.partial=false] Specify if the cursor should return partial results when querying against a sharded system
+ * @param {number} [options.maxTimeMS] Number of milliseconds to wait before aborting the query.
+ * @param {number} [options.maxAwaitTimeMS] The maximum amount of time for the server to wait on new documents to satisfy a tailable cursor query. Requires `tailable` and `awaitData` to be true
+ * @param {boolean} [options.noCursorTimeout] The server normally times out idle cursors after an inactivity period (10 minutes) to prevent excess memory use. Set this option to prevent that.
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {boolean} [options.allowDiskUse] Enables writing to temporary files on the server.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @throws {MongoError}
+ * @return {Cursor}
+ */
+Collection.prototype.find = deprecateOptions(
+  {
+    name: 'collection.find',
+    deprecatedOptions: DEPRECATED_FIND_OPTIONS,
+    optionsIndex: 1
+  },
+  function(query, options, callback) {
+    if (typeof callback === 'object') {
+      // TODO(MAJOR): throw in the future
+      console.warn('Third parameter to `find()` must be a callback or undefined');
+    }
+
+    let selector = query;
+    // figuring out arguments
+    if (typeof callback !== 'function') {
+      if (typeof options === 'function') {
+        callback = options;
+        options = undefined;
+      } else if (options == null) {
+        callback = typeof selector === 'function' ? selector : undefined;
+        selector = typeof selector === 'object' ? selector : undefined;
+      }
+    }
+
+    // Ensure selector is not null
+    selector = selector == null ? {} : selector;
+    // Validate correctness off the selector
+    const object = selector;
+    if (Buffer.isBuffer(object)) {
+      const object_size = object[0] | (object[1] << 8) | (object[2] << 16) | (object[3] << 24);
+      if (object_size !== object.length) {
+        const error = new Error(
+          'query selector raw message size does not match message header size [' +
+            object.length +
+            '] != [' +
+            object_size +
+            ']'
+        );
+        error.name = 'MongoError';
+        throw error;
+      }
+    }
+
+    // Check special case where we are using an objectId
+    if (selector != null && selector._bsontype === 'ObjectID') {
+      selector = { _id: selector };
+    }
+
+    if (!options) options = {};
+
+    let projection = options.projection || options.fields;
+
+    if (projection && !Buffer.isBuffer(projection) && Array.isArray(projection)) {
+      projection = projection.length
+        ? projection.reduce((result, field) => {
+            result[field] = 1;
+            return result;
+          }, {})
+        : { _id: 1 };
+    }
+
+    // Make a shallow copy of options
+    let newOptions = Object.assign({}, options);
+
+    // Make a shallow copy of the collection options
+    for (let key in this.s.options) {
+      if (mergeKeys.indexOf(key) !== -1) {
+        newOptions[key] = this.s.options[key];
+      }
+    }
+
+    // Unpack options
+    newOptions.skip = options.skip ? options.skip : 0;
+    newOptions.limit = options.limit ? options.limit : 0;
+    newOptions.raw = typeof options.raw === 'boolean' ? options.raw : this.s.raw;
+    newOptions.hint =
+      options.hint != null ? normalizeHintField(options.hint) : this.s.collectionHint;
+    newOptions.timeout = typeof options.timeout === 'undefined' ? undefined : options.timeout;
+    // // If we have overridden slaveOk otherwise use the default db setting
+    newOptions.slaveOk = options.slaveOk != null ? options.slaveOk : this.s.db.slaveOk;
+
+    // Add read preference if needed
+    newOptions.readPreference = ReadPreference.resolve(this, newOptions);
+
+    // Set slave ok to true if read preference different from primary
+    if (
+      newOptions.readPreference != null &&
+      (newOptions.readPreference !== 'primary' || newOptions.readPreference.mode !== 'primary')
+    ) {
+      newOptions.slaveOk = true;
+    }
+
+    // Ensure the query is an object
+    if (selector != null && typeof selector !== 'object') {
+      throw MongoError.create({ message: 'query selector must be an object', driver: true });
+    }
+
+    // Build the find command
+    const findCommand = {
+      find: this.s.namespace.toString(),
+      limit: newOptions.limit,
+      skip: newOptions.skip,
+      query: selector
+    };
+
+    if (typeof options.allowDiskUse === 'boolean') {
+      findCommand.allowDiskUse = options.allowDiskUse;
+    }
+
+    // Ensure we use the right await data option
+    if (typeof newOptions.awaitdata === 'boolean') {
+      newOptions.awaitData = newOptions.awaitdata;
+    }
+
+    // Translate to new command option noCursorTimeout
+    if (typeof newOptions.timeout === 'boolean') newOptions.noCursorTimeout = newOptions.timeout;
+
+    decorateCommand(findCommand, newOptions, ['session', 'collation']);
+
+    if (projection) findCommand.fields = projection;
+
+    // Add db object to the new options
+    newOptions.db = this.s.db;
+
+    // Add the promise library
+    newOptions.promiseLibrary = this.s.promiseLibrary;
+
+    // Set raw if available at collection level
+    if (newOptions.raw == null && typeof this.s.raw === 'boolean') newOptions.raw = this.s.raw;
+    // Set promoteLongs if available at collection level
+    if (newOptions.promoteLongs == null && typeof this.s.promoteLongs === 'boolean')
+      newOptions.promoteLongs = this.s.promoteLongs;
+    if (newOptions.promoteValues == null && typeof this.s.promoteValues === 'boolean')
+      newOptions.promoteValues = this.s.promoteValues;
+    if (newOptions.promoteBuffers == null && typeof this.s.promoteBuffers === 'boolean')
+      newOptions.promoteBuffers = this.s.promoteBuffers;
+
+    // Sort options
+    if (findCommand.sort) {
+      findCommand.sort = formattedOrderClause(findCommand.sort);
+    }
+
+    // Set the readConcern
+    decorateWithReadConcern(findCommand, this, options);
+
+    // Decorate find command with collation options
+    try {
+      decorateWithCollation(findCommand, this, options);
+    } catch (err) {
+      if (typeof callback === 'function') return callback(err, null);
+      throw err;
+    }
+
+    const cursor = this.s.topology.cursor(
+      new FindOperation(this, this.s.namespace, findCommand, newOptions),
+      newOptions
+    );
+
+    // TODO: remove this when NODE-2074 is resolved
+    if (typeof callback === 'function') {
+      callback(null, cursor);
+      return;
+    }
+
+    return cursor;
+  }
+);
+
+/**
+ * Inserts a single document into MongoDB. If documents passed in do not contain the **_id** field,
+ * one will be added to each of the documents missing it by the driver, mutating the document. This behavior
+ * can be overridden by setting the **forceServerObjectId** flag.
+ *
+ * @method
+ * @param {object} doc Document to insert.
+ * @param {object} [options] Optional settings.
+ * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {boolean} [options.forceServerObjectId=false] Force server to assign _id values instead of driver.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.checkKeys=true] If true, will throw if bson documents start with `$` or include a `.` in any key value
+ * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~insertOneWriteOpCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.insertOne = function(doc, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  // Add ignoreUndefined
+  if (this.s.options.ignoreUndefined) {
+    options = Object.assign({}, options);
+    options.ignoreUndefined = this.s.options.ignoreUndefined;
+  }
+
+  const insertOneOperation = new InsertOneOperation(this, doc, options);
+
+  return executeOperation(this.s.topology, insertOneOperation, callback);
+};
+
+/**
+ * Inserts an array of documents into MongoDB. If documents passed in do not contain the **_id** field,
+ * one will be added to each of the documents missing it by the driver, mutating the document. This behavior
+ * can be overridden by setting the **forceServerObjectId** flag.
+ *
+ * @method
+ * @param {object[]} docs Documents to insert.
+ * @param {object} [options] Optional settings.
+ * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {boolean} [options.ordered=true] If true, when an insert fails, don't execute the remaining writes. If false, continue with remaining inserts when one fails.
+ * @param {boolean} [options.forceServerObjectId=false] Force server to assign _id values instead of driver.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.checkKeys=true] If true, will throw if bson documents start with `$` or include a `.` in any key value
+ * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~insertWriteOpCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.insertMany = function(docs, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options ? Object.assign({}, options) : { ordered: true };
+
+  const insertManyOperation = new InsertManyOperation(this, docs, options);
+
+  return executeOperation(this.s.topology, insertManyOperation, callback);
+};
+
+/**
+ * @typedef {Object} Collection~BulkWriteOpResult
+ * @property {number} insertedCount Number of documents inserted.
+ * @property {number} matchedCount Number of documents matched for update.
+ * @property {number} modifiedCount Number of documents modified.
+ * @property {number} deletedCount Number of documents deleted.
+ * @property {number} upsertedCount Number of documents upserted.
+ * @property {object} insertedIds Inserted document generated Id's, hash key is the index of the originating operation
+ * @property {object} upsertedIds Upserted document generated Id's, hash key is the index of the originating operation
+ * @property {object} result The command result object.
+ */
+
+/**
+ * The callback format for inserts
+ * @callback Collection~bulkWriteOpCallback
+ * @param {BulkWriteError} error An error instance representing the error during the execution.
+ * @param {Collection~BulkWriteOpResult} result The result object if the command was executed successfully.
+ */
+
+/**
+ * Perform a bulkWrite operation without a fluent API
+ *
+ * Legal operation types are
+ *
+ *  { insertOne: { document: { a: 1 } } }
+ *
+ *  { updateOne: { filter: {a:2}, update: {$set: {a:2}}, upsert:true } }
+ *
+ *  { updateMany: { filter: {a:2}, update: {$set: {a:2}}, upsert:true } }
+ *
+ *  { updateMany: { filter: {}, update: {$set: {"a.$[i].x": 5}}, arrayFilters: [{ "i.x": 5 }]} }
+ *
+ *  { deleteOne: { filter: {c:1} } }
+ *
+ *  { deleteMany: { filter: {c:1} } }
+ *
+ *  { replaceOne: { filter: {c:3}, replacement: {c:4}, upsert:true}}
+ *
+ * If documents passed in do not contain the **_id** field,
+ * one will be added to each of the documents missing it by the driver, mutating the document. This behavior
+ * can be overridden by setting the **forceServerObjectId** flag.
+ *
+ * @method
+ * @param {object[]} operations Bulk operations to perform.
+ * @param {object} [options] Optional settings.
+ * @param {boolean} [options.ordered=true] Execute write operation in ordered or unordered fashion.
+ * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {object[]} [options.arrayFilters] Determines which array elements to modify for update operation in MongoDB 3.6 or higher.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.checkKeys=false] If true, will throw if bson documents start with `$` or include a `.` in any key value
+ * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~bulkWriteOpCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.bulkWrite = function(operations, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || { ordered: true };
+
+  if (!Array.isArray(operations)) {
+    throw MongoError.create({ message: 'operations must be an array of documents', driver: true });
+  }
+
+  const bulkWriteOperation = new BulkWriteOperation(this, operations, options);
+
+  return executeOperation(this.s.topology, bulkWriteOperation, callback);
+};
+
+/**
+ * @typedef {Object} Collection~WriteOpResult
+ * @property {object[]} ops All the documents inserted using insertOne/insertMany/replaceOne. Documents contain the _id field if forceServerObjectId == false for insertOne/insertMany
+ * @property {object} connection The connection object used for the operation.
+ * @property {object} result The command result object.
+ */
+
+/**
+ * The callback format for inserts
+ * @callback Collection~writeOpCallback
+ * @param {MongoError} error An error instance representing the error during the execution.
+ * @param {Collection~WriteOpResult} result The result object if the command was executed successfully.
+ */
+
+/**
+ * @typedef {Object} Collection~insertWriteOpResult
+ * @property {number} insertedCount The total amount of documents inserted.
+ * @property {object[]} ops All the documents inserted using insertOne/insertMany/replaceOne. Documents contain the _id field if forceServerObjectId == false for insertOne/insertMany
+ * @property {Object.<Number, ObjectId>} insertedIds Map of the index of the inserted document to the id of the inserted document.
+ * @property {object} connection The connection object used for the operation.
+ * @property {object} result The raw command result object returned from MongoDB (content might vary by server version).
+ * @property {number} result.ok Is 1 if the command executed correctly.
+ * @property {number} result.n The total count of documents inserted.
+ */
+
+/**
+ * @typedef {Object} Collection~insertOneWriteOpResult
+ * @property {number} insertedCount The total amount of documents inserted.
+ * @property {object[]} ops All the documents inserted using insertOne/insertMany/replaceOne. Documents contain the _id field if forceServerObjectId == false for insertOne/insertMany
+ * @property {ObjectId} insertedId The driver generated ObjectId for the insert operation.
+ * @property {object} connection The connection object used for the operation.
+ * @property {object} result The raw command result object returned from MongoDB (content might vary by server version).
+ * @property {number} result.ok Is 1 if the command executed correctly.
+ * @property {number} result.n The total count of documents inserted.
+ */
+
+/**
+ * The callback format for inserts
+ * @callback Collection~insertWriteOpCallback
+ * @param {MongoError} error An error instance representing the error during the execution.
+ * @param {Collection~insertWriteOpResult} result The result object if the command was executed successfully.
+ */
+
+/**
+ * The callback format for inserts
+ * @callback Collection~insertOneWriteOpCallback
+ * @param {MongoError} error An error instance representing the error during the execution.
+ * @param {Collection~insertOneWriteOpResult} result The result object if the command was executed successfully.
+ */
+
+/**
+ * Inserts a single document or a an array of documents into MongoDB. If documents passed in do not contain the **_id** field,
+ * one will be added to each of the documents missing it by the driver, mutating the document. This behavior
+ * can be overridden by setting the **forceServerObjectId** flag.
+ *
+ * @method
+ * @param {(object|object[])} docs Documents to insert.
+ * @param {object} [options] Optional settings.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
+ * @param {boolean} [options.forceServerObjectId=false] Force server to assign _id values instead of driver.
+ * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~insertWriteOpCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ * @deprecated Use insertOne, insertMany or bulkWrite
+ */
+Collection.prototype.insert = deprecate(function(docs, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || { ordered: false };
+  docs = !Array.isArray(docs) ? [docs] : docs;
+
+  if (options.keepGoing === true) {
+    options.ordered = false;
+  }
+
+  return this.insertMany(docs, options, callback);
+}, 'collection.insert is deprecated. Use insertOne, insertMany or bulkWrite instead.');
+
+/**
+ * @typedef {Object} Collection~updateWriteOpResult
+ * @property {Object} result The raw result returned from MongoDB. Will vary depending on server version.
+ * @property {Number} result.ok Is 1 if the command executed correctly.
+ * @property {Number} result.n The total count of documents scanned.
+ * @property {Number} result.nModified The total count of documents modified.
+ * @property {Object} connection The connection object used for the operation.
+ * @property {Number} matchedCount The number of documents that matched the filter.
+ * @property {Number} modifiedCount The number of documents that were modified.
+ * @property {Number} upsertedCount The number of documents upserted.
+ * @property {Object} upsertedId The upserted id.
+ * @property {ObjectId} upsertedId._id The upserted _id returned from the server.
+ * @property {Object} message The raw msg response wrapped in an internal class
+ * @property {object[]} [ops] In a response to {@link Collection#replaceOne replaceOne}, contains the new value of the document on the server. This is the same document that was originally passed in, and is only here for legacy purposes.
+ */
+
+/**
+ * The callback format for inserts
+ * @callback Collection~updateWriteOpCallback
+ * @param {MongoError} error An error instance representing the error during the execution.
+ * @param {Collection~updateWriteOpResult} result The result object if the command was executed successfully.
+ */
+
+/**
+ * Update a single document in a collection
+ * @method
+ * @param {object} filter The Filter used to select the document to update
+ * @param {object} update The update operations to be applied to the document
+ * @param {object} [options] Optional settings.
+ * @param {Array} [options.arrayFilters] optional list of array filters referenced in filtered positional operators
+ * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {object} [options.hint] An optional hint for query optimization. See the {@link https://docs.mongodb.com/manual/reference/command/update/#update-command-hint|update command} reference for more information.
+ * @param {boolean} [options.upsert=false] When true, creates a new document if no document matches the query..
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.checkKeys=false] If true, will throw if bson documents start with `$` or include a `.` in any key value
+ * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~updateWriteOpCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.updateOne = function(filter, update, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = Object.assign({}, options);
+
+  // Add ignoreUndefined
+  if (this.s.options.ignoreUndefined) {
+    options = Object.assign({}, options);
+    options.ignoreUndefined = this.s.options.ignoreUndefined;
+  }
+
+  return executeOperation(
+    this.s.topology,
+    new UpdateOneOperation(this, filter, update, options),
+    callback
+  );
+};
+
+/**
+ * Replace a document in a collection with another document
+ * @method
+ * @param {object} filter The Filter used to select the document to replace
+ * @param {object} doc The Document that replaces the matching document
+ * @param {object} [options] Optional settings.
+ * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {object} [options.hint] An optional hint for query optimization. See the {@link https://docs.mongodb.com/manual/reference/command/update/#update-command-hint|update command} reference for more information.
+ * @param {boolean} [options.upsert=false] When true, creates a new document if no document matches the query.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.checkKeys=false] If true, will throw if bson documents start with `$` or include a `.` in any key value
+ * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~updateWriteOpCallback} [callback] The command result callback
+ * @return {Promise<Collection~updateWriteOpResult>} returns Promise if no callback passed
+ */
+Collection.prototype.replaceOne = function(filter, doc, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = Object.assign({}, options);
+
+  // Add ignoreUndefined
+  if (this.s.options.ignoreUndefined) {
+    options = Object.assign({}, options);
+    options.ignoreUndefined = this.s.options.ignoreUndefined;
+  }
+
+  return executeOperation(
+    this.s.topology,
+    new ReplaceOneOperation(this, filter, doc, options),
+    callback
+  );
+};
+
+/**
+ * Update multiple documents in a collection
+ * @method
+ * @param {object} filter The Filter used to select the documents to update
+ * @param {object} update The update operations to be applied to the documents
+ * @param {object} [options] Optional settings.
+ * @param {Array} [options.arrayFilters] optional list of array filters referenced in filtered positional operators
+ * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {object} [options.hint] An optional hint for query optimization. See the {@link https://docs.mongodb.com/manual/reference/command/update/#update-command-hint|update command} reference for more information.
+ * @param {boolean} [options.upsert=false] When true, creates a new document if no document matches the query..
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.checkKeys=false] If true, will throw if bson documents start with `$` or include a `.` in any key value
+ * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~updateWriteOpCallback} [callback] The command result callback
+ * @return {Promise<Collection~updateWriteOpResult>} returns Promise if no callback passed
+ */
+Collection.prototype.updateMany = function(filter, update, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = Object.assign({}, options);
+
+  // Add ignoreUndefined
+  if (this.s.options.ignoreUndefined) {
+    options = Object.assign({}, options);
+    options.ignoreUndefined = this.s.options.ignoreUndefined;
+  }
+
+  return executeOperation(
+    this.s.topology,
+    new UpdateManyOperation(this, filter, update, options),
+    callback
+  );
+};
+
+/**
+ * Updates documents.
+ * @method
+ * @param {object} selector The selector for the update operation.
+ * @param {object} update The update operations to be applied to the documents
+ * @param {object} [options] Optional settings.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.upsert=false] Update operation is an upsert.
+ * @param {boolean} [options.multi=false] Update one/all documents with operation.
+ * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {Array} [options.arrayFilters] optional list of array filters referenced in filtered positional operators
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {object} [options.hint] An optional hint for query optimization. See the {@link https://docs.mongodb.com/manual/reference/command/update/#update-command-hint|update command} reference for more information.
+ * @param {Collection~writeOpCallback} [callback] The command result callback
+ * @throws {MongoError}
+ * @return {Promise} returns Promise if no callback passed
+ * @deprecated use updateOne, updateMany or bulkWrite
+ */
+Collection.prototype.update = deprecate(function(selector, update, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  // Add ignoreUndefined
+  if (this.s.options.ignoreUndefined) {
+    options = Object.assign({}, options);
+    options.ignoreUndefined = this.s.options.ignoreUndefined;
+  }
+
+  return executeLegacyOperation(this.s.topology, updateDocuments, [
+    this,
+    selector,
+    update,
+    options,
+    callback
+  ]);
+}, 'collection.update is deprecated. Use updateOne, updateMany, or bulkWrite instead.');
+
+/**
+ * @typedef {Object} Collection~deleteWriteOpResult
+ * @property {Object} result The raw result returned from MongoDB. Will vary depending on server version.
+ * @property {Number} result.ok Is 1 if the command executed correctly.
+ * @property {Number} result.n The total count of documents deleted.
+ * @property {Object} connection The connection object used for the operation.
+ * @property {Number} deletedCount The number of documents deleted.
+ */
+
+/**
+ * The callback format for deletes
+ * @callback Collection~deleteWriteOpCallback
+ * @param {MongoError} error An error instance representing the error during the execution.
+ * @param {Collection~deleteWriteOpResult} result The result object if the command was executed successfully.
+ */
+
+/**
+ * Delete a document from a collection
+ * @method
+ * @param {object} filter The Filter used to select the document to remove
+ * @param {object} [options] Optional settings.
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.checkKeys=false] If true, will throw if bson documents start with `$` or include a `.` in any key value
+ * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {string|object} [options.hint] optional index hint for optimizing the filter query
+ * @param {Collection~deleteWriteOpCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.deleteOne = function(filter, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = Object.assign({}, options);
+
+  // Add ignoreUndefined
+  if (this.s.options.ignoreUndefined) {
+    options = Object.assign({}, options);
+    options.ignoreUndefined = this.s.options.ignoreUndefined;
+  }
+
+  const deleteOneOperation = new DeleteOneOperation(this, filter, options);
+
+  return executeOperation(this.s.topology, deleteOneOperation, callback);
+};
+
+Collection.prototype.removeOne = Collection.prototype.deleteOne;
+
+/**
+ * Delete multiple documents from a collection
+ * @method
+ * @param {object} filter The Filter used to select the documents to remove
+ * @param {object} [options] Optional settings.
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.checkKeys=false] If true, will throw if bson documents start with `$` or include a `.` in any key value
+ * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {string|object} [options.hint] optional index hint for optimizing the filter query
+ * @param {Collection~deleteWriteOpCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.deleteMany = function(filter, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = Object.assign({}, options);
+
+  // Add ignoreUndefined
+  if (this.s.options.ignoreUndefined) {
+    options = Object.assign({}, options);
+    options.ignoreUndefined = this.s.options.ignoreUndefined;
+  }
+
+  const deleteManyOperation = new DeleteManyOperation(this, filter, options);
+
+  return executeOperation(this.s.topology, deleteManyOperation, callback);
+};
+
+Collection.prototype.removeMany = Collection.prototype.deleteMany;
+
+/**
+ * Remove documents.
+ * @method
+ * @param {object} selector The selector for the update operation.
+ * @param {object} [options] Optional settings.
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.single=false] Removes the first document found.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~writeOpCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ * @deprecated use deleteOne, deleteMany or bulkWrite
+ */
+Collection.prototype.remove = deprecate(function(selector, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  // Add ignoreUndefined
+  if (this.s.options.ignoreUndefined) {
+    options = Object.assign({}, options);
+    options.ignoreUndefined = this.s.options.ignoreUndefined;
+  }
+
+  return executeLegacyOperation(this.s.topology, removeDocuments, [
+    this,
+    selector,
+    options,
+    callback
+  ]);
+}, 'collection.remove is deprecated. Use deleteOne, deleteMany, or bulkWrite instead.');
+
+/**
+ * Save a document. Simple full document replacement function. Not recommended for efficiency, use atomic
+ * operators and update instead for more efficient operations.
+ * @method
+ * @param {object} doc Document to save
+ * @param {object} [options] Optional settings.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~writeOpCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ * @deprecated use insertOne, insertMany, updateOne or updateMany
+ */
+Collection.prototype.save = deprecate(function(doc, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  // Add ignoreUndefined
+  if (this.s.options.ignoreUndefined) {
+    options = Object.assign({}, options);
+    options.ignoreUndefined = this.s.options.ignoreUndefined;
+  }
+
+  return executeLegacyOperation(this.s.topology, save, [this, doc, options, callback]);
+}, 'collection.save is deprecated. Use insertOne, insertMany, updateOne, or updateMany instead.');
+
+/**
+ * The callback format for results
+ * @callback Collection~resultCallback
+ * @param {MongoError} error An error instance representing the error during the execution.
+ * @param {object} result The result object if the command was executed successfully.
+ */
+
+/**
+ * The callback format for an aggregation call
+ * @callback Collection~aggregationCallback
+ * @param {MongoError} error An error instance representing the error during the execution.
+ * @param {AggregationCursor} cursor The cursor if the aggregation command was executed successfully.
+ */
+
+/**
+ * Fetches the first document that matches the query
+ * @method
+ * @param {object} query Query for find Operation
+ * @param {object} [options] Optional settings.
+ * @param {number} [options.limit=0] Sets the limit of documents returned in the query.
+ * @param {(array|object)} [options.sort] Set to sort the documents coming back from the query. Array of indexes, [['a', 1]] etc.
+ * @param {object} [options.projection] The fields to return in the query. Object of fields to include or exclude (not both), {'a':1}
+ * @param {object} [options.fields] **Deprecated** Use `options.projection` instead
+ * @param {number} [options.skip=0] Set to skip N documents ahead in your query (useful for pagination).
+ * @param {Object} [options.hint] Tell the query to use specific indexes in the query. Object of indexes to use, {'_id':1}
+ * @param {boolean} [options.explain=false] Explain the query instead of returning the data.
+ * @param {boolean} [options.snapshot=false] DEPRECATED: Snapshot query.
+ * @param {boolean} [options.timeout=false] Specify if the cursor can timeout.
+ * @param {boolean} [options.tailable=false] Specify if the cursor is tailable.
+ * @param {number} [options.batchSize=1] Set the batchSize for the getMoreCommand when iterating over the query results.
+ * @param {boolean} [options.returnKey=false] Only return the index key.
+ * @param {number} [options.maxScan] DEPRECATED: Limit the number of items to scan.
+ * @param {number} [options.min] Set index bounds.
+ * @param {number} [options.max] Set index bounds.
+ * @param {boolean} [options.showDiskLoc=false] Show disk location of results.
+ * @param {string} [options.comment] You can put a $comment field on a query to make looking in the profiler logs simpler.
+ * @param {boolean} [options.raw=false] Return document results as raw BSON buffers.
+ * @param {boolean} [options.promoteLongs=true] Promotes Long values to number if they fit inside the 53 bits resolution.
+ * @param {boolean} [options.promoteValues=true] Promotes BSON values to native types where possible, set to false to only receive wrapper types.
+ * @param {boolean} [options.promoteBuffers=false] Promotes Binary BSON values to native Node Buffers.
+ * @param {(ReadPreference|string)} [options.readPreference] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
+ * @param {boolean} [options.partial=false] Specify if the cursor should return partial results when querying against a sharded system
+ * @param {number} [options.maxTimeMS] Number of milliseconds to wait before aborting the query.
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.findOne = deprecateOptions(
+  {
+    name: 'collection.find',
+    deprecatedOptions: DEPRECATED_FIND_OPTIONS,
+    optionsIndex: 1
+  },
+  function(query, options, callback) {
+    if (typeof callback === 'object') {
+      // TODO(MAJOR): throw in the future
+      console.warn('Third parameter to `findOne()` must be a callback or undefined');
+    }
+
+    if (typeof query === 'function') (callback = query), (query = {}), (options = {});
+    if (typeof options === 'function') (callback = options), (options = {});
+    query = query || {};
+    options = options || {};
+
+    const findOneOperation = new FindOneOperation(this, query, options);
+
+    return executeOperation(this.s.topology, findOneOperation, callback);
+  }
+);
+
+/**
+ * The callback format for the collection method, must be used if strict is specified
+ * @callback Collection~collectionResultCallback
+ * @param {MongoError} error An error instance representing the error during the execution.
+ * @param {Collection} collection The collection instance.
+ */
+
+/**
+ * Rename the collection.
+ *
+ * @method
+ * @param {string} newName New name of of the collection.
+ * @param {object} [options] Optional settings.
+ * @param {boolean} [options.dropTarget=false] Drop the target name collection if it previously exists.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~collectionResultCallback} [callback] The results callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.rename = function(newName, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = Object.assign({}, options, { readPreference: ReadPreference.PRIMARY });
+
+  const renameOperation = new RenameOperation(this, newName, options);
+
+  return executeOperation(this.s.topology, renameOperation, callback);
+};
+
+/**
+ * Drop the collection from the database, removing it permanently. New accesses will create a new collection.
+ *
+ * @method
+ * @param {object} [options] Optional settings.
+ * @param {WriteConcern} [options.writeConcern] A full WriteConcern object
+ * @param {(number|string)} [options.w] The write concern
+ * @param {number} [options.wtimeout] The write concern timeout
+ * @param {boolean} [options.j] The journal write concern
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The results callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.drop = function(options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  const dropCollectionOperation = new DropCollectionOperation(
+    this.s.db,
+    this.collectionName,
+    options
+  );
+
+  return executeOperation(this.s.topology, dropCollectionOperation, callback);
+};
+
+/**
+ * Returns the options of the collection.
+ *
+ * @method
+ * @param {Object} [options] Optional settings
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The results callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.options = function(opts, callback) {
+  if (typeof opts === 'function') (callback = opts), (opts = {});
+  opts = opts || {};
+
+  const optionsOperation = new OptionsOperation(this, opts);
+
+  return executeOperation(this.s.topology, optionsOperation, callback);
+};
+
+/**
+ * Returns if the collection is a capped collection
+ *
+ * @method
+ * @param {Object} [options] Optional settings
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The results callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.isCapped = function(options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  const isCappedOperation = new IsCappedOperation(this, options);
+
+  return executeOperation(this.s.topology, isCappedOperation, callback);
+};
+
+/**
+ * Creates an index on the db and collection collection.
+ * @method
+ * @param {(string|array|object)} fieldOrSpec Defines the index.
+ * @param {object} [options] Optional settings.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.unique=false] Creates an unique index.
+ * @param {boolean} [options.sparse=false] Creates a sparse index.
+ * @param {boolean} [options.background=false] Creates the index in the background, yielding whenever possible.
+ * @param {boolean} [options.dropDups=false] A unique index cannot be created on a key that has pre-existing duplicate values. If you would like to create the index anyway, keeping the first document the database indexes and deleting all subsequent documents that have duplicate value
+ * @param {number} [options.min] For geospatial indexes set the lower bound for the co-ordinates.
+ * @param {number} [options.max] For geospatial indexes set the high bound for the co-ordinates.
+ * @param {number} [options.v] Specify the format version of the indexes.
+ * @param {number} [options.expireAfterSeconds] Allows you to expire data on indexes applied to a data (MongoDB 2.2 or higher)
+ * @param {string} [options.name] Override the autogenerated index name (useful if the resulting name is larger than 128 bytes)
+ * @param {object} [options.partialFilterExpression] Creates a partial index based on the given filter object (MongoDB 3.2 or higher)
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {(number|string)} [options.commitQuorum] (MongoDB 4.4. or higher) Specifies how many data-bearing members of a replica set, including the primary, must complete the index builds successfully before the primary marks the indexes as ready. This option accepts the same values for the "w" field in a write concern plus "votingMembers", which indicates all voting data-bearing nodes.
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ * @example
+ * const collection = client.db('foo').collection('bar');
+ *
+ * await collection.createIndex({ a: 1, b: -1 });
+ *
+ * // Alternate syntax for { c: 1, d: -1 } that ensures order of indexes
+ * await collection.createIndex([ [c, 1], [d, -1] ]);
+ *
+ * // Equivalent to { e: 1 }
+ * await collection.createIndex('e');
+ *
+ * // Equivalent to { f: 1, g: 1 }
+ * await collection.createIndex(['f', 'g'])
+ *
+ * // Equivalent to { h: 1, i: -1 }
+ * await collection.createIndex([ { h: 1 }, { i: -1 } ]);
+ *
+ * // Equivalent to { j: 1, k: -1, l: 2d }
+ * await collection.createIndex(['j', ['k', -1], { l: '2d' }])
+ */
+Collection.prototype.createIndex = function(fieldOrSpec, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  const createIndexesOperation = new CreateIndexesOperation(
+    this,
+    this.collectionName,
+    fieldOrSpec,
+    options
+  );
+
+  return executeOperation(this.s.topology, createIndexesOperation, callback);
+};
+
+/**
+ * @typedef {object} Collection~IndexDefinition
+ * @description A definition for an index. Used by the createIndex command.
+ * @see https://docs.mongodb.com/manual/reference/command/createIndexes/
+ */
+
+/**
+ * Creates multiple indexes in the collection, this method is only supported for
+ * MongoDB 2.6 or higher. Earlier version of MongoDB will throw a command not supported
+ * error.
+ *
+ * **Note**: Unlike {@link Collection#createIndex createIndex}, this function takes in raw index specifications.
+ * Index specifications are defined {@link http://docs.mongodb.org/manual/reference/command/createIndexes/ here}.
+ *
+ * @method
+ * @param {Collection~IndexDefinition[]} indexSpecs An array of index specifications to be created
+ * @param {Object} [options] Optional settings
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {(number|string)} [options.commitQuorum] (MongoDB 4.4. or higher) Specifies how many data-bearing members of a replica set, including the primary, must complete the index builds successfully before the primary marks the indexes as ready. This option accepts the same values for the "w" field in a write concern plus "votingMembers", which indicates all voting data-bearing nodes.
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ * @example
+ * const collection = client.db('foo').collection('bar');
+ * await collection.createIndexes([
+ *   // Simple index on field fizz
+ *   {
+ *     key: { fizz: 1 },
+ *   }
+ *   // wildcard index
+ *   {
+ *     key: { '$**': 1 }
+ *   },
+ *   // named index on darmok and jalad
+ *   {
+ *     key: { darmok: 1, jalad: -1 }
+ *     name: 'tanagra'
+ *   }
+ * ]);
+ */
+Collection.prototype.createIndexes = function(indexSpecs, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+
+  options = options ? Object.assign({}, options) : {};
+
+  if (typeof options.maxTimeMS !== 'number') delete options.maxTimeMS;
+
+  const createIndexesOperation = new CreateIndexesOperation(
+    this,
+    this.collectionName,
+    indexSpecs,
+    options
+  );
+
+  return executeOperation(this.s.topology, createIndexesOperation, callback);
+};
+
+/**
+ * Drops an index from this collection.
+ * @method
+ * @param {string} indexName Name of the index to drop.
+ * @param {object} [options] Optional settings.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {number} [options.maxTimeMS] Number of milliseconds to wait before aborting the query.
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.dropIndex = function(indexName, options, callback) {
+  const args = Array.prototype.slice.call(arguments, 1);
+  callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
+
+  options = args.length ? args.shift() || {} : {};
+  // Run only against primary
+  options.readPreference = ReadPreference.PRIMARY;
+
+  const dropIndexOperation = new DropIndexOperation(this, indexName, options);
+
+  return executeOperation(this.s.topology, dropIndexOperation, callback);
+};
+
+/**
+ * Drops all indexes from this collection.
+ * @method
+ * @param {Object} [options] Optional settings
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {number} [options.maxTimeMS] Number of milliseconds to wait before aborting the query.
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.dropIndexes = function(options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options ? Object.assign({}, options) : {};
+
+  if (typeof options.maxTimeMS !== 'number') delete options.maxTimeMS;
+
+  const dropIndexesOperation = new DropIndexesOperation(this, options);
+
+  return executeOperation(this.s.topology, dropIndexesOperation, callback);
+};
+
+/**
+ * Drops all indexes from this collection.
+ * @method
+ * @deprecated use dropIndexes
+ * @param {Collection~resultCallback} callback The command result callback
+ * @return {Promise} returns Promise if no [callback] passed
+ */
+Collection.prototype.dropAllIndexes = deprecate(
+  Collection.prototype.dropIndexes,
+  'collection.dropAllIndexes is deprecated. Use dropIndexes instead.'
+);
+
+/**
+ * Reindex all indexes on the collection
+ * Warning: reIndex is a blocking operation (indexes are rebuilt in the foreground) and will be slow for large collections.
+ * @method
+ * @deprecated use db.command instead
+ * @param {Object} [options] Optional settings
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.reIndex = deprecate(function(options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  const reIndexOperation = new ReIndexOperation(this, options);
+
+  return executeOperation(this.s.topology, reIndexOperation, callback);
+}, 'collection.reIndex is deprecated. Use db.command instead.');
+
+/**
+ * Get the list of all indexes information for the collection.
+ *
+ * @method
+ * @param {object} [options] Optional settings.
+ * @param {number} [options.batchSize=1000] The batchSize for the returned command cursor or if pre 2.8 the systems batch collection
+ * @param {(ReadPreference|string)} [options.readPreference] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @return {CommandCursor}
+ */
+Collection.prototype.listIndexes = function(options) {
+  const cursor = new CommandCursor(
+    this.s.topology,
+    new ListIndexesOperation(this, options),
+    options
+  );
+
+  return cursor;
+};
+
+/**
+ * Ensures that an index exists, if it does not it creates it
+ * @method
+ * @deprecated use createIndexes instead
+ * @param {(string|object)} fieldOrSpec Defines the index.
+ * @param {object} [options] Optional settings.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.unique=false] Creates an unique index.
+ * @param {boolean} [options.sparse=false] Creates a sparse index.
+ * @param {boolean} [options.background=false] Creates the index in the background, yielding whenever possible.
+ * @param {boolean} [options.dropDups=false] A unique index cannot be created on a key that has pre-existing duplicate values. If you would like to create the index anyway, keeping the first document the database indexes and deleting all subsequent documents that have duplicate value
+ * @param {number} [options.min] For geospatial indexes set the lower bound for the co-ordinates.
+ * @param {number} [options.max] For geospatial indexes set the high bound for the co-ordinates.
+ * @param {number} [options.v] Specify the format version of the indexes.
+ * @param {number} [options.expireAfterSeconds] Allows you to expire data on indexes applied to a data (MongoDB 2.2 or higher)
+ * @param {number} [options.name] Override the autogenerated index name (useful if the resulting name is larger than 128 bytes)
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.ensureIndex = deprecate(function(fieldOrSpec, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  return executeLegacyOperation(this.s.topology, ensureIndex, [
+    this,
+    fieldOrSpec,
+    options,
+    callback
+  ]);
+}, 'collection.ensureIndex is deprecated. Use createIndexes instead.');
+
+/**
+ * Checks if one or more indexes exist on the collection, fails on first non-existing index
+ * @method
+ * @param {(string|array)} indexes One or more index names to check.
+ * @param {Object} [options] Optional settings
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.indexExists = function(indexes, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  const indexExistsOperation = new IndexExistsOperation(this, indexes, options);
+
+  return executeOperation(this.s.topology, indexExistsOperation, callback);
+};
+
+/**
+ * Retrieves this collections index info.
+ * @method
+ * @param {object} [options] Optional settings.
+ * @param {boolean} [options.full=false] Returns the full raw index information.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.indexInformation = function(options, callback) {
+  const args = Array.prototype.slice.call(arguments, 0);
+  callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
+  options = args.length ? args.shift() || {} : {};
+
+  const indexInformationOperation = new IndexInformationOperation(
+    this.s.db,
+    this.collectionName,
+    options
+  );
+
+  return executeOperation(this.s.topology, indexInformationOperation, callback);
+};
+
+/**
+ * The callback format for results
+ * @callback Collection~countCallback
+ * @param {MongoError} error An error instance representing the error during the execution.
+ * @param {number} result The count of documents that matched the query.
+ */
+
+/**
+ * An estimated count of matching documents in the db to a query.
+ *
+ * **NOTE:** This method has been deprecated, since it does not provide an accurate count of the documents
+ * in a collection. To obtain an accurate count of documents in the collection, use {@link Collection#countDocuments countDocuments}.
+ * To obtain an estimated count of all documents in the collection, use {@link Collection#estimatedDocumentCount estimatedDocumentCount}.
+ *
+ * @method
+ * @param {object} [query={}] The query for the count.
+ * @param {object} [options] Optional settings.
+ * @param {object} [options.collation] Specify collation settings for operation. See {@link https://docs.mongodb.com/manual/reference/command/aggregate|aggregation documentation}.
+ * @param {boolean} [options.limit] The limit of documents to count.
+ * @param {boolean} [options.skip] The number of documents to skip for the count.
+ * @param {string} [options.hint] An index name hint for the query.
+ * @param {(ReadPreference|string)} [options.readPreference] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
+ * @param {number} [options.maxTimeMS] Number of milliseconds to wait before aborting the query.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~countCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ * @deprecated use {@link Collection#countDocuments countDocuments} or {@link Collection#estimatedDocumentCount estimatedDocumentCount} instead
+ */
+Collection.prototype.count = deprecate(function(query, options, callback) {
+  const args = Array.prototype.slice.call(arguments, 0);
+  callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
+  query = args.length ? args.shift() || {} : {};
+  options = args.length ? args.shift() || {} : {};
+
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  return executeOperation(
+    this.s.topology,
+    new EstimatedDocumentCountOperation(this, query, options),
+    callback
+  );
+}, 'collection.count is deprecated, and will be removed in a future version.' +
+  ' Use Collection.countDocuments or Collection.estimatedDocumentCount instead');
+
+/**
+ * Gets an estimate of the count of documents in a collection using collection metadata.
+ *
+ * @method
+ * @param {object} [options] Optional settings.
+ * @param {number} [options.maxTimeMS] The maximum amount of time to allow the operation to run.
+ * @param {Collection~countCallback} [callback] The command result callback.
+ * @return {Promise} returns Promise if no callback passed.
+ */
+Collection.prototype.estimatedDocumentCount = function(options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  const estimatedDocumentCountOperation = new EstimatedDocumentCountOperation(this, options);
+
+  return executeOperation(this.s.topology, estimatedDocumentCountOperation, callback);
+};
+
+/**
+ * Gets the number of documents matching the filter.
+ * For a fast count of the total documents in a collection see {@link Collection#estimatedDocumentCount estimatedDocumentCount}.
+ * **Note**: When migrating from {@link Collection#count count} to {@link Collection#countDocuments countDocuments}
+ * the following query operators must be replaced:
+ *
+ * | Operator | Replacement |
+ * | -------- | ----------- |
+ * | `$where`   | [`$expr`][1] |
+ * | `$near`    | [`$geoWithin`][2] with [`$center`][3] |
+ * | `$nearSphere` | [`$geoWithin`][2] with [`$centerSphere`][4] |
+ *
+ * [1]: https://docs.mongodb.com/manual/reference/operator/query/expr/
+ * [2]: https://docs.mongodb.com/manual/reference/operator/query/geoWithin/
+ * [3]: https://docs.mongodb.com/manual/reference/operator/query/center/#op._S_center
+ * [4]: https://docs.mongodb.com/manual/reference/operator/query/centerSphere/#op._S_centerSphere
+ *
+ * @param {object} [query] the query for the count
+ * @param {object} [options] Optional settings.
+ * @param {object} [options.collation] Specifies a collation.
+ * @param {string|object} [options.hint] The index to use.
+ * @param {number} [options.limit] The maximum number of document to count.
+ * @param {number} [options.maxTimeMS] The maximum amount of time to allow the operation to run.
+ * @param {number} [options.skip] The number of documents to skip before counting.
+ * @param {Collection~countCallback} [callback] The command result callback.
+ * @return {Promise} returns Promise if no callback passed.
+ * @see https://docs.mongodb.com/manual/reference/operator/query/expr/
+ * @see https://docs.mongodb.com/manual/reference/operator/query/geoWithin/
+ * @see https://docs.mongodb.com/manual/reference/operator/query/center/#op._S_center
+ * @see https://docs.mongodb.com/manual/reference/operator/query/centerSphere/#op._S_centerSphere
+ */
+
+Collection.prototype.countDocuments = function(query, options, callback) {
+  const args = Array.prototype.slice.call(arguments, 0);
+  callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
+  query = args.length ? args.shift() || {} : {};
+  options = args.length ? args.shift() || {} : {};
+
+  const countDocumentsOperation = new CountDocumentsOperation(this, query, options);
+
+  return executeOperation(this.s.topology, countDocumentsOperation, callback);
+};
+
+/**
+ * The distinct command returns a list of distinct values for the given key across a collection.
+ * @method
+ * @param {string} key Field of the document to find distinct values for.
+ * @param {object} [query] The query for filtering the set of documents to which we apply the distinct filter.
+ * @param {object} [options] Optional settings.
+ * @param {(ReadPreference|string)} [options.readPreference] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
+ * @param {number} [options.maxTimeMS] Number of milliseconds to wait before aborting the query.
+ * @param {object} [options.collation] Specify collation settings for operation. See {@link https://docs.mongodb.com/manual/reference/command/aggregate|aggregation documentation}.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.distinct = function(key, query, options, callback) {
+  const args = Array.prototype.slice.call(arguments, 1);
+  callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
+  const queryOption = args.length ? args.shift() || {} : {};
+  const optionsOption = args.length ? args.shift() || {} : {};
+
+  const distinctOperation = new DistinctOperation(this, key, queryOption, optionsOption);
+
+  return executeOperation(this.s.topology, distinctOperation, callback);
+};
+
+/**
+ * Retrieve all the indexes on the collection.
+ * @method
+ * @param {Object} [options] Optional settings
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.indexes = function(options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  const indexesOperation = new IndexesOperation(this, options);
+
+  return executeOperation(this.s.topology, indexesOperation, callback);
+};
+
+/**
+ * Get all the collection statistics.
+ *
+ * @method
+ * @param {object} [options] Optional settings.
+ * @param {number} [options.scale] Divide the returned sizes by scale value.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The collection result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.stats = function(options, callback) {
+  const args = Array.prototype.slice.call(arguments, 0);
+  callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
+  options = args.length ? args.shift() || {} : {};
+
+  const statsOperation = new StatsOperation(this, options);
+
+  return executeOperation(this.s.topology, statsOperation, callback);
+};
+
+/**
+ * @typedef {Object} Collection~findAndModifyWriteOpResult
+ * @property {object} value Document returned from the `findAndModify` command. If no documents were found, `value` will be `null` by default (`returnOriginal: true`), even if a document was upserted; if `returnOriginal` was false, the upserted document will be returned in that case.
+ * @property {object} lastErrorObject The raw lastErrorObject returned from the command. See {@link https://docs.mongodb.com/manual/reference/command/findAndModify/index.html#lasterrorobject|findAndModify command documentation}.
+ * @property {Number} ok Is 1 if the command executed correctly.
+ */
+
+/**
+ * The callback format for inserts
+ * @callback Collection~findAndModifyCallback
+ * @param {MongoError} error An error instance representing the error during the execution.
+ * @param {Collection~findAndModifyWriteOpResult} result The result object if the command was executed successfully.
+ */
+
+/**
+ * Find a document and delete it in one atomic operation. Requires a write lock for the duration of the operation.
+ *
+ * @method
+ * @param {object} filter The Filter used to select the document to remove
+ * @param {object} [options] Optional settings.
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {object} [options.projection] Limits the fields to return for all matching documents.
+ * @param {object} [options.sort] Determines which document the operation modifies if the query selects multiple documents.
+ * @param {number} [options.maxTimeMS] The maximum amount of time to allow the query to run.
+ * @param {boolean} [options.checkKeys=false] If true, will throw if bson documents start with `$` or include a `.` in any key value
+ * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~findAndModifyCallback} [callback] The collection result callback
+ * @return {Promise<Collection~findAndModifyWriteOpResultObject>} returns Promise if no callback passed
+ */
+Collection.prototype.findOneAndDelete = function(filter, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  return executeOperation(
+    this.s.topology,
+    new FindOneAndDeleteOperation(this, filter, options),
+    callback
+  );
+};
+
+/**
+ * Find a document and replace it in one atomic operation. Requires a write lock for the duration of the operation.
+ *
+ * @method
+ * @param {object} filter The Filter used to select the document to replace
+ * @param {object} replacement The Document that replaces the matching document
+ * @param {object} [options] Optional settings.
+ * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {string|object} [options.hint] An optional index to use for this operation
+ * @param {number} [options.maxTimeMS] The maximum amount of time to allow the query to run.
+ * @param {object} [options.projection] Limits the fields to return for all matching documents.
+ * @param {object} [options.sort] Determines which document the operation modifies if the query selects multiple documents.
+ * @param {boolean} [options.upsert=false] Upsert the document if it does not exist.
+ * @param {boolean} [options.returnOriginal=true] When false, returns the updated document rather than the original. The default is true.
+ * @param {boolean} [options.checkKeys=false] If true, will throw if bson documents start with `$` or include a `.` in any key value
+ * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~findAndModifyCallback} [callback] The collection result callback
+ * @return {Promise<Collection~findAndModifyWriteOpResultObject>} returns Promise if no callback passed
+ */
+Collection.prototype.findOneAndReplace = function(filter, replacement, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  return executeOperation(
+    this.s.topology,
+    new FindOneAndReplaceOperation(this, filter, replacement, options),
+    callback
+  );
+};
+
+/**
+ * Find a document and update it in one atomic operation. Requires a write lock for the duration of the operation.
+ *
+ * @method
+ * @param {object} filter The Filter used to select the document to update
+ * @param {object} update Update operations to be performed on the document
+ * @param {object} [options] Optional settings.
+ * @param {Array} [options.arrayFilters] optional list of array filters referenced in filtered positional operators
+ * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {object} [options.collation] Specify collation (MongoDB 3.4 or higher) settings for update operation (see 3.4 documentation for available fields).
+ * @param {string|object} [options.hint] An optional index to use for this operation
+ * @param {number} [options.maxTimeMS] The maximum amount of time to allow the query to run.
+ * @param {object} [options.projection] Limits the fields to return for all matching documents.
+ * @param {object} [options.sort] Determines which document the operation modifies if the query selects multiple documents.
+ * @param {boolean} [options.upsert=false] Upsert the document if it does not exist.
+ * @param {boolean} [options.returnOriginal=true] When false, returns the updated document rather than the original. The default is true.
+ * @param {boolean} [options.checkKeys=false] If true, will throw if bson documents start with `$` or include a `.` in any key value
+ * @param {boolean} [options.serializeFunctions=false] Serialize functions on any object.
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {ClientSession} [options.session] An ptional session to use for this operation
+ * @param {Collection~findAndModifyCallback} [callback] The collection result callback
+ * @return {Promise<Collection~findAndModifyWriteOpResultObject>} returns Promise if no callback passed
+ */
+Collection.prototype.findOneAndUpdate = function(filter, update, options, callback) {
+  if (typeof options === 'function') (callback = options), (options = {});
+  options = options || {};
+
+  return executeOperation(
+    this.s.topology,
+    new FindOneAndUpdateOperation(this, filter, update, options),
+    callback
+  );
+};
+
+/**
+ * Find and update a document.
+ * @method
+ * @param {object} query Query object to locate the object to modify.
+ * @param {array} sort If multiple docs match, choose the first one in the specified sort order as the object to manipulate.
+ * @param {object} doc The fields/vals to be updated.
+ * @param {object} [options] Optional settings.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.remove=false] Set to true to remove the object before returning.
+ * @param {boolean} [options.upsert=false] Perform an upsert operation.
+ * @param {boolean} [options.new=false] Set to true if you want to return the modified object rather than the original. Ignored for remove.
+ * @param {object} [options.projection] Object containing the field projection for the result returned from the operation.
+ * @param {object} [options.fields] **Deprecated** Use `options.projection` instead
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Array} [options.arrayFilters] optional list of array filters referenced in filtered positional operators
+ * @param {Collection~findAndModifyCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ * @deprecated use findOneAndUpdate, findOneAndReplace or findOneAndDelete instead
+ */
+Collection.prototype.findAndModify = deprecate(
+  _findAndModify,
+  'collection.findAndModify is deprecated. Use findOneAndUpdate, findOneAndReplace or findOneAndDelete instead.'
+);
+
+/**
+ * @ignore
+ */
+
+Collection.prototype._findAndModify = _findAndModify;
+
+function _findAndModify(query, sort, doc, options, callback) {
+  const args = Array.prototype.slice.call(arguments, 1);
+  callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
+  sort = args.length ? args.shift() || [] : [];
+  doc = args.length ? args.shift() : null;
+  options = args.length ? args.shift() || {} : {};
+
+  // Clone options
+  options = Object.assign({}, options);
+  // Force read preference primary
+  options.readPreference = ReadPreference.PRIMARY;
+
+  return executeOperation(
+    this.s.topology,
+    new FindAndModifyOperation(this, query, sort, doc, options),
+    callback
+  );
+}
+
+/**
+ * Find and remove a document.
+ * @method
+ * @param {object} query Query object to locate the object to modify.
+ * @param {array} sort If multiple docs match, choose the first one in the specified sort order as the object to manipulate.
+ * @param {object} [options] Optional settings.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ * @deprecated use findOneAndDelete instead
+ */
+Collection.prototype.findAndRemove = deprecate(function(query, sort, options, callback) {
+  const args = Array.prototype.slice.call(arguments, 1);
+  callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
+  sort = args.length ? args.shift() || [] : [];
+  options = args.length ? args.shift() || {} : {};
+
+  // Add the remove option
+  options.remove = true;
+
+  return executeOperation(
+    this.s.topology,
+    new FindAndModifyOperation(this, query, sort, null, options),
+    callback
+  );
+}, 'collection.findAndRemove is deprecated. Use findOneAndDelete instead.');
+
+/**
+ * Execute an aggregation framework pipeline against the collection, needs MongoDB >= 2.2
+ * @method
+ * @param {object} [pipeline=[]] Array containing all the aggregation framework commands for the execution.
+ * @param {object} [options] Optional settings.
+ * @param {(ReadPreference|string)} [options.readPreference] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
+ * @param {number} [options.batchSize=1000] The number of documents to return per batch. See {@link https://docs.mongodb.com/manual/reference/command/aggregate|aggregation documentation}.
+ * @param {object} [options.cursor] Return the query as cursor, on 2.6 > it returns as a real cursor on pre 2.6 it returns as an emulated cursor.
+ * @param {number} [options.cursor.batchSize=1000] Deprecated. Use `options.batchSize`
+ * @param {boolean} [options.explain=false] Explain returns the aggregation execution plan (requires mongodb 2.6 >).
+ * @param {boolean} [options.allowDiskUse=false] allowDiskUse lets the server know if it can use disk to store temporary results for the aggregation (requires mongodb 2.6 >).
+ * @param {number} [options.maxTimeMS] maxTimeMS specifies a cumulative time limit in milliseconds for processing operations on the cursor. MongoDB interrupts the operation at the earliest following interrupt point.
+ * @param {number} [options.maxAwaitTimeMS] The maximum amount of time for the server to wait on new documents to satisfy a tailable cursor query.
+ * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {boolean} [options.raw=false] Return document results as raw BSON buffers.
+ * @param {boolean} [options.promoteLongs=true] Promotes Long values to number if they fit inside the 53 bits resolution.
+ * @param {boolean} [options.promoteValues=true] Promotes BSON values to native types where possible, set to false to only receive wrapper types.
+ * @param {boolean} [options.promoteBuffers=false] Promotes Binary BSON values to native Node Buffers.
+ * @param {object} [options.collation] Specify collation settings for operation. See {@link https://docs.mongodb.com/manual/reference/command/aggregate|aggregation documentation}.
+ * @param {string} [options.comment] Add a comment to an aggregation command
+ * @param {string|object} [options.hint] Add an index selection hint to an aggregation command
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~aggregationCallback} callback The command result callback
+ * @return {(null|AggregationCursor)}
+ */
+Collection.prototype.aggregate = function(pipeline, options, callback) {
+  if (Array.isArray(pipeline)) {
+    // Set up callback if one is provided
+    if (typeof options === 'function') {
+      callback = options;
+      options = {};
+    }
+
+    // If we have no options or callback we are doing
+    // a cursor based aggregation
+    if (options == null && callback == null) {
+      options = {};
+    }
+  } else {
+    // Aggregation pipeline passed as arguments on the method
+    const args = Array.prototype.slice.call(arguments, 0);
+    // Get the callback
+    callback = args.pop();
+    // Get the possible options object
+    const opts = args[args.length - 1];
+    // If it contains any of the admissible options pop it of the args
+    options =
+      opts &&
+      (opts.readPreference ||
+        opts.explain ||
+        opts.cursor ||
+        opts.out ||
+        opts.maxTimeMS ||
+        opts.hint ||
+        opts.allowDiskUse)
+        ? args.pop()
+        : {};
+    // Left over arguments is the pipeline
+    pipeline = args;
+  }
+
+  const cursor = new AggregationCursor(
+    this.s.topology,
+    new AggregateOperation(this, pipeline, options),
+    options
+  );
+
+  // TODO: remove this when NODE-2074 is resolved
+  if (typeof callback === 'function') {
+    callback(null, cursor);
+    return;
+  }
+
+  return cursor;
+};
+
+/**
+ * Create a new Change Stream, watching for new changes (insertions, updates, replacements, deletions, and invalidations) in this collection.
+ * @method
+ * @since 3.0.0
+ * @param {Array} [pipeline] An array of {@link https://docs.mongodb.com/manual/reference/operator/aggregation-pipeline/|aggregation pipeline stages} through which to pass change stream documents. This allows for filtering (using $match) and manipulating the change stream documents.
+ * @param {object} [options] Optional settings
+ * @param {string} [options.fullDocument='default'] Allowed values: ‘default’, ‘updateLookup’. When set to ‘updateLookup’, the change stream will include both a delta describing the changes to the document, as well as a copy of the entire document that was changed from some time after the change occurred.
+ * @param {object} [options.resumeAfter] Specifies the logical starting point for the new change stream. This should be the _id field from a previously returned change stream document.
+ * @param {number} [options.maxAwaitTimeMS] The maximum amount of time for the server to wait on new documents to satisfy a change stream query
+ * @param {number} [options.batchSize=1000] The number of documents to return per batch. See {@link https://docs.mongodb.com/manual/reference/command/aggregate|aggregation documentation}.
+ * @param {object} [options.collation] Specify collation settings for operation. See {@link https://docs.mongodb.com/manual/reference/command/aggregate|aggregation documentation}.
+ * @param {ReadPreference} [options.readPreference] The read preference. Defaults to the read preference of the database or collection. See {@link https://docs.mongodb.com/manual/reference/read-preference|read preference documentation}.
+ * @param {Timestamp} [options.startAtOperationTime] receive change events that occur after the specified timestamp
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @return {ChangeStream} a ChangeStream instance.
+ */
+Collection.prototype.watch = function(pipeline, options) {
+  pipeline = pipeline || [];
+  options = options || {};
+
+  // Allow optionally not specifying a pipeline
+  if (!Array.isArray(pipeline)) {
+    options = pipeline;
+    pipeline = [];
+  }
+
+  return new ChangeStream(this, pipeline, options);
+};
+
+/**
+ * The callback format for results
+ * @callback Collection~parallelCollectionScanCallback
+ * @param {MongoError} error An error instance representing the error during the execution.
+ * @param {Cursor[]} cursors A list of cursors returned allowing for parallel reading of collection.
+ */
+
+/**
+ * Return N number of parallel cursors for a collection allowing parallel reading of entire collection. There are
+ * no ordering guarantees for returned results.
+ * @method
+ * @param {object} [options] Optional settings.
+ * @param {(ReadPreference|string)} [options.readPreference] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
+ * @param {number} [options.batchSize=1000] Set the batchSize for the getMoreCommand when iterating over the query results.
+ * @param {number} [options.numCursors=1] The maximum number of parallel command cursors to return (the number of returned cursors will be in the range 1:numCursors)
+ * @param {boolean} [options.raw=false] Return all BSON documents as Raw Buffer documents.
+ * @param {Collection~parallelCollectionScanCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.parallelCollectionScan = deprecate(function(options, callback) {
+  if (typeof options === 'function') (callback = options), (options = { numCursors: 1 });
+  // Set number of cursors to 1
+  options.numCursors = options.numCursors || 1;
+  options.batchSize = options.batchSize || 1000;
+
+  options = Object.assign({}, options);
+  // Ensure we have the right read preference inheritance
+  options.readPreference = ReadPreference.resolve(this, options);
+
+  // Add a promiseLibrary
+  options.promiseLibrary = this.s.promiseLibrary;
+
+  if (options.session) {
+    options.session = undefined;
+  }
+
+  return executeLegacyOperation(
+    this.s.topology,
+    parallelCollectionScan,
+    [this, options, callback],
+    { skipSessions: true }
+  );
+}, 'parallelCollectionScan is deprecated in MongoDB v4.1');
+
+/**
+ * Execute a geo search using a geo haystack index on a collection.
+ *
+ * @method
+ * @param {number} x Point to search on the x axis, ensure the indexes are ordered in the same order.
+ * @param {number} y Point to search on the y axis, ensure the indexes are ordered in the same order.
+ * @param {object} [options] Optional settings.
+ * @param {(ReadPreference|string)} [options.readPreference] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
+ * @param {number} [options.maxDistance] Include results up to maxDistance from the point.
+ * @param {object} [options.search] Filter the results by a query.
+ * @param {number} [options.limit=false] Max number of results to return.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ * @deprecated See {@link https://docs.mongodb.com/manual/geospatial-queries/|geospatial queries docs} for current geospatial support
+ */
+Collection.prototype.geoHaystackSearch = deprecate(function(x, y, options, callback) {
+  const args = Array.prototype.slice.call(arguments, 2);
+  callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
+  options = args.length ? args.shift() || {} : {};
+
+  const geoHaystackSearchOperation = new GeoHaystackSearchOperation(this, x, y, options);
+
+  return executeOperation(this.s.topology, geoHaystackSearchOperation, callback);
+}, 'geoHaystackSearch is deprecated, and will be removed in a future version.');
+
+/**
+ * Run a group command across a collection
+ *
+ * @method
+ * @param {(object|array|function|code)} keys An object, array or function expressing the keys to group by.
+ * @param {object} condition An optional condition that must be true for a row to be considered.
+ * @param {object} initial Initial value of the aggregation counter object.
+ * @param {(function|Code)} reduce The reduce function aggregates (reduces) the objects iterated
+ * @param {(function|Code)} finalize An optional function to be run on each item in the result set just before the item is returned.
+ * @param {boolean} command Specify if you wish to run using the internal group command or using eval, default is true.
+ * @param {object} [options] Optional settings.
+ * @param {(ReadPreference|string)} [options.readPreference] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @return {Promise} returns Promise if no callback passed
+ * @deprecated MongoDB 3.6 or higher no longer supports the group command. We recommend rewriting using the aggregation framework.
+ */
+Collection.prototype.group = deprecate(function(
+  keys,
+  condition,
+  initial,
+  reduce,
+  finalize,
+  command,
+  options,
+  callback
+) {
+  const args = Array.prototype.slice.call(arguments, 3);
+  callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
+  reduce = args.length ? args.shift() : null;
+  finalize = args.length ? args.shift() : null;
+  command = args.length ? args.shift() : null;
+  options = args.length ? args.shift() || {} : {};
+
+  // Make sure we are backward compatible
+  if (!(typeof finalize === 'function')) {
+    command = finalize;
+    finalize = null;
+  }
+
+  if (
+    !Array.isArray(keys) &&
+    keys instanceof Object &&
+    typeof keys !== 'function' &&
+    !(keys._bsontype === 'Code')
+  ) {
+    keys = Object.keys(keys);
+  }
+
+  if (typeof reduce === 'function') {
+    reduce = reduce.toString();
+  }
+
+  if (typeof finalize === 'function') {
+    finalize = finalize.toString();
+  }
+
+  // Set up the command as default
+  command = command == null ? true : command;
+
+  return executeLegacyOperation(this.s.topology, group, [
+    this,
+    keys,
+    condition,
+    initial,
+    reduce,
+    finalize,
+    command,
+    options,
+    callback
+  ]);
+},
+'MongoDB 3.6 or higher no longer supports the group command. We recommend rewriting using the aggregation framework.');
+
+/**
+ * Run Map Reduce across a collection. Be aware that the inline option for out will return an array of results not a collection.
+ *
+ * @method
+ * @param {(function|string)} map The mapping function.
+ * @param {(function|string)} reduce The reduce function.
+ * @param {object} [options] Optional settings.
+ * @param {(ReadPreference|string)} [options.readPreference] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
+ * @param {object} [options.out] Sets the output target for the map reduce job. *{inline:1} | {replace:'collectionName'} | {merge:'collectionName'} | {reduce:'collectionName'}*
+ * @param {object} [options.query] Query filter object.
+ * @param {object} [options.sort] Sorts the input objects using this key. Useful for optimization, like sorting by the emit key for fewer reduces.
+ * @param {number} [options.limit] Number of objects to return from collection.
+ * @param {boolean} [options.keeptemp=false] Keep temporary data.
+ * @param {(function|string)} [options.finalize] Finalize function.
+ * @param {object} [options.scope] Can pass in variables that can be access from map/reduce/finalize.
+ * @param {boolean} [options.jsMode=false] It is possible to make the execution stay in JS. Provided in MongoDB > 2.0.X.
+ * @param {boolean} [options.verbose=false] Provide statistics on job execution time.
+ * @param {boolean} [options.bypassDocumentValidation=false] Allow driver to bypass schema validation in MongoDB 3.2 or higher.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {Collection~resultCallback} [callback] The command result callback
+ * @throws {MongoError}
+ * @return {Promise} returns Promise if no callback passed
+ */
+Collection.prototype.mapReduce = function(map, reduce, options, callback) {
+  if ('function' === typeof options) (callback = options), (options = {});
+  // Out must allways be defined (make sure we don't break weirdly on pre 1.8+ servers)
+  if (null == options.out) {
+    throw new Error(
+      'the out option parameter must be defined, see mongodb docs for possible values'
+    );
+  }
+
+  if ('function' === typeof map) {
+    map = map.toString();
+  }
+
+  if ('function' === typeof reduce) {
+    reduce = reduce.toString();
+  }
+
+  if ('function' === typeof options.finalize) {
+    options.finalize = options.finalize.toString();
+  }
+  const mapReduceOperation = new MapReduceOperation(this, map, reduce, options);
+
+  return executeOperation(this.s.topology, mapReduceOperation, callback);
+};
+
+/**
+ * Initiate an Out of order batch write operation. All operations will be buffered into insert/update/remove commands executed out of order.
+ *
+ * @method
+ * @param {object} [options] Optional settings.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @return {UnorderedBulkOperation}
+ */
+Collection.prototype.initializeUnorderedBulkOp = function(options) {
+  options = options || {};
+  // Give function's options precedence over session options.
+  if (options.ignoreUndefined == null) {
+    options.ignoreUndefined = this.s.options.ignoreUndefined;
+  }
+
+  options.promiseLibrary = this.s.promiseLibrary;
+  return unordered(this.s.topology, this, options);
+};
+
+/**
+ * Initiate an In order bulk write operation. Operations will be serially executed in the order they are added, creating a new operation for each switch in types.
+ *
+ * @method
+ * @param {object} [options] Optional settings.
+ * @param {(number|string)} [options.w] The write concern.
+ * @param {number} [options.wtimeout] The write concern timeout.
+ * @param {boolean} [options.j=false] Specify a journal write concern.
+ * @param {ClientSession} [options.session] optional session to use for this operation
+ * @param {boolean} [options.ignoreUndefined=false] Specify if the BSON serializer should ignore undefined fields.
+ * @param {OrderedBulkOperation} callback The command result callback
+ * @return {null}
+ */
+Collection.prototype.initializeOrderedBulkOp = function(options) {
+  options = options || {};
+  // Give function's options precedence over session's options.
+  if (options.ignoreUndefined == null) {
+    options.ignoreUndefined = this.s.options.ignoreUndefined;
+  }
+  options.promiseLibrary = this.s.promiseLibrary;
+  return ordered(this.s.topology, this, options);
+};
+
+/**
+ * Return the db logger
+ * @method
+ * @return {Logger} return the db logger
+ * @ignore
+ */
+Collection.prototype.getLogger = function() {
+  return this.s.db.s.logger;
+};
+
+module.exports = Collection;