Node.js MongoDB Driver API

Source: lib/gridfs/grid_store.js

'use strict';
/**
 * @fileOverview GridFS is a tool for MongoDB to store files to the database.
 * Because of the restrictions of the object size the database can hold, a
 * facility to split a file into several chunks is needed. The {@link GridStore}
 * class offers a simplified api to interact with files while managing the
 * chunks of split files behind the scenes. More information about GridFS can be
 * found <a href="http://www.mongodb.org/display/DOCS/GridFS">here</a>.
 *
 * @example
 * const MongoClient = require('mongodb').MongoClient;
 * const GridStore = require('mongodb').GridStore;
 * const ObjectID = require('mongodb').ObjectID;
 * 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) {
 * const db = client.db(dbName);
 * const gridStore = new GridStore(db, null, "w");
 * gridStore.open(function(err, gridStore) {
 * gridStore.write("hello world!", function(err, gridStore) {
 * gridStore.close(function(err, result) {
 * // Let's read the file using object Id
 * GridStore.read(db, result._id, function(err, data) {
 * test.equal('hello world!', data);
 * client.close();
 * test.done();
 * });
 * });
 * });
 * });
 * });
 */
const Chunk = require('./chunk');
const ObjectID = require('../core').BSON.ObjectID;
const ReadPreference = require('../core').ReadPreference;
const Buffer = require('safe-buffer').Buffer;
const fs = require('fs');
const f = require('util').format;
const util = require('util');
const MongoError = require('../core').MongoError;
const inherits = util.inherits;
const Duplex = require('stream').Duplex;
const shallowClone = require('../utils').shallowClone;
const executeLegacyOperation = require('../utils').executeLegacyOperation;
const deprecate = require('util').deprecate;
var REFERENCE_BY_FILENAME = 0,
 REFERENCE_BY_ID = 1;
const deprecationFn = deprecate(() => {},
'GridStore is deprecated, and will be removed in a future version. Please use GridFSBucket instead');
/**
 * Namespace provided by the core module
 * @external Duplex
 */
/**
 * Create a new GridStore instance
 *
 * Modes
 * - **"r"** - read only. This is the default mode.
 * - **"w"** - write in truncate mode. Existing data will be overwritten.
 *
 * @class
 * @param {Db} db A database instance to interact with.
 * @param {object} [id] optional unique id for this file
 * @param {string} [filename] optional filename for this file, no unique constrain on the field
 * @param {string} mode set the mode for this file.
 * @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.fsync=false] Specify a file sync write concern.
 * @param {string} [options.root] Root collection to use. Defaults to **{GridStore.DEFAULT_ROOT_COLLECTION}**.
 * @param {string} [options.content_type] MIME type of the file. Defaults to **{GridStore.DEFAULT_CONTENT_TYPE}**.
 * @param {number} [options.chunk_size=261120] Size for the chunk. Defaults to **{Chunk.DEFAULT_CHUNK_SIZE}**.
 * @param {object} [options.metadata] Arbitrary data the user wants to store.
 * @param {object} [options.promiseLibrary] A Promise library class the application wishes to use such as Bluebird, must be ES6 compatible
 * @param {(ReadPreference|string)} [options.readPreference] The preferred read preference (ReadPreference.PRIMARY, ReadPreference.PRIMARY_PREFERRED, ReadPreference.SECONDARY, ReadPreference.SECONDARY_PREFERRED, ReadPreference.NEAREST).
 * @property {number} chunkSize Get the gridstore chunk size.
 * @property {number} md5 The md5 checksum for this file.
 * @property {number} chunkNumber The current chunk number the gridstore has materialized into memory
 * @return {GridStore} a GridStore instance.
 * @deprecated Use GridFSBucket API instead
 */
var GridStore = function GridStore(db, id, filename, mode, options) {
 deprecationFn();
 if (!(this instanceof GridStore)) return new GridStore(db, id, filename, mode, options);
 this.db = db;
 // Handle options
 if (typeof options === 'undefined') options = {};
 // Handle mode
 if (typeof mode === 'undefined') {
 mode = filename;
 filename = undefined;
 } else if (typeof mode === 'object') {
 options = mode;
 mode = filename;
 filename = undefined;
 }
 if (id && id._bsontype === 'ObjectID') {
 this.referenceBy = REFERENCE_BY_ID;
 this.fileId = id;
 this.filename = filename;
 } else if (typeof filename === 'undefined') {
 this.referenceBy = REFERENCE_BY_FILENAME;
 this.filename = id;
 if (mode.indexOf('w') != null) {
 this.fileId = new ObjectID();
 }
 } else {
 this.referenceBy = REFERENCE_BY_ID;
 this.fileId = id;
 this.filename = filename;
 }
 // Set up the rest
 this.mode = mode == null ? 'r' : mode;
 this.options = options || {};
 // Opened
 this.isOpen = false;
 // Set the root if overridden
 this.root =
 this.options['root'] == null ? GridStore.DEFAULT_ROOT_COLLECTION : this.options['root'];
 this.position = 0;
 this.readPreference =
 this.options.readPreference || db.options.readPreference || ReadPreference.primary;
 this.writeConcern = _getWriteConcern(db, this.options);
 // Set default chunk size
 this.internalChunkSize =
 this.options['chunkSize'] == null ? Chunk.DEFAULT_CHUNK_SIZE : this.options['chunkSize'];
 // Get the promiseLibrary
 var promiseLibrary = this.options.promiseLibrary || Promise;
 // Set the promiseLibrary
 this.promiseLibrary = promiseLibrary;
 Object.defineProperty(this, 'chunkSize', {
 enumerable: true,
 get: function() {
 return this.internalChunkSize;
 },
 set: function(value) {
 if (!(this.mode[0] === 'w' && this.position === 0 && this.uploadDate == null)) {
 this.internalChunkSize = this.internalChunkSize;
 } else {
 this.internalChunkSize = value;
 }
 }
 });
 Object.defineProperty(this, 'md5', {
 enumerable: true,
 get: function() {
 return this.internalMd5;
 }
 });
 Object.defineProperty(this, 'chunkNumber', {
 enumerable: true,
 get: function() {
 return this.currentChunk && this.currentChunk.chunkNumber
 ? this.currentChunk.chunkNumber
 : null;
 }
 });
};
/**
 * The callback format for the Gridstore.open method
 * @callback GridStore~openCallback
 * @param {MongoError} error An error instance representing the error during the execution.
 * @param {GridStore} gridStore The GridStore instance if the open method was successful.
 */
/**
 * Opens the file from the database and initialize this object. Also creates a
 * new one if file does not exist.
 *
 * @method
 * @param {object} [options] Optional settings
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~openCallback} [callback] this will be called after executing this method
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.open = function(options, callback) {
 if (typeof options === 'function') (callback = options), (options = {});
 options = options || {};
 if (this.mode !== 'w' && this.mode !== 'w+' && this.mode !== 'r') {
 throw MongoError.create({ message: 'Illegal mode ' + this.mode, driver: true });
 }
 return executeLegacyOperation(this.db.s.topology, open, [this, options, callback], {
 skipSessions: true
 });
};
var open = function(self, options, callback) {
 // Get the write concern
 var writeConcern = _getWriteConcern(self.db, self.options);
 // If we are writing we need to ensure we have the right indexes for md5's
 if (self.mode === 'w' || self.mode === 'w+') {
 // Get files collection
 var collection = self.collection();
 // Put index on filename
 collection.ensureIndex([['filename', 1]], writeConcern, function() {
 // Get chunk collection
 var chunkCollection = self.chunkCollection();
 // Make an unique index for compatibility with mongo-cxx-driver:legacy
 var chunkIndexOptions = shallowClone(writeConcern);
 chunkIndexOptions.unique = true;
 // Ensure index on chunk collection
 chunkCollection.ensureIndex(
 [
 ['files_id', 1],
 ['n', 1]
 ],
 chunkIndexOptions,
 function() {
 // Open the connection
 _open(self, writeConcern, function(err, r) {
 if (err) return callback(err);
 self.isOpen = true;
 callback(err, r);
 });
 }
 );
 });
 } else {
 // Open the gridstore
 _open(self, writeConcern, function(err, r) {
 if (err) return callback(err);
 self.isOpen = true;
 callback(err, r);
 });
 }
};
/**
 * Verify if the file is at EOF.
 *
 * @method
 * @return {boolean} true if the read/write head is at the end of this file.
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.eof = function() {
 return this.position === this.length ? true : false;
};
/**
 * The callback result format.
 * @callback GridStore~resultCallback
 * @param {object} [options] Optional settings
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {MongoError} error An error instance representing the error during the execution.
 * @param {object} result The result from the callback.
 */
/**
 * Retrieves a single character from this file.
 *
 * @method
 * @param {GridStore~resultCallback} [callback] this gets called after this method is executed. Passes null to the first parameter and the character read to the second or null to the second if the read/write head is at the end of the file.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.getc = function(options, callback) {
 if (typeof options === 'function') (callback = options), (options = {});
 options = options || {};
 return executeLegacyOperation(this.db.s.topology, getc, [this, options, callback], {
 skipSessions: true
 });
};
var getc = function(self, options, callback) {
 if (self.eof()) {
 callback(null, null);
 } else if (self.currentChunk.eof()) {
 nthChunk(self, self.currentChunk.chunkNumber + 1, function(err, chunk) {
 self.currentChunk = chunk;
 self.position = self.position + 1;
 callback(err, self.currentChunk.getc());
 });
 } else {
 self.position = self.position + 1;
 callback(null, self.currentChunk.getc());
 }
};
/**
 * Writes a string to the file with a newline character appended at the end if
 * the given string does not have one.
 *
 * @method
 * @param {string} string the string to write.
 * @param {object} [options] Optional settings
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~resultCallback} [callback] this will be called after executing this method. The first parameter will contain null and the second one will contain a reference to this object.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.puts = function(string, options, callback) {
 if (typeof options === 'function') (callback = options), (options = {});
 options = options || {};
 var finalString = string.match(/\n$/) == null ? string + '\n' : string;
 return executeLegacyOperation(
 this.db.s.topology,
 this.write.bind(this),
 [finalString, options, callback],
 { skipSessions: true }
 );
};
/**
 * Return a modified Readable stream including a possible transform method.
 *
 * @method
 * @return {GridStoreStream}
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.stream = function() {
 return new GridStoreStream(this);
};
/**
 * Writes some data. This method will work properly only if initialized with mode "w" or "w+".
 *
 * @method
 * @param {(string|Buffer)} data the data to write.
 * @param {boolean} [close] closes this file after writing if set to true.
 * @param {object} [options] Optional settings
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~resultCallback} [callback] this will be called after executing this method. The first parameter will contain null and the second one will contain a reference to this object.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.write = function write(data, close, options, callback) {
 if (typeof options === 'function') (callback = options), (options = {});
 options = options || {};
 return executeLegacyOperation(
 this.db.s.topology,
 _writeNormal,
 [this, data, close, options, callback],
 { skipSessions: true }
 );
};
/**
 * Handles the destroy part of a stream
 *
 * @method
 * @result {null}
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.destroy = function destroy() {
 // close and do not emit any more events. queued data is not sent.
 if (!this.writable) return;
 this.readable = false;
 if (this.writable) {
 this.writable = false;
 this._q.length = 0;
 this.emit('close');
 }
};
/**
 * Stores a file from the file system to the GridFS database.
 *
 * @method
 * @param {(string|Buffer|FileHandle)} file the file to store.
 * @param {object} [options] Optional settings
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~resultCallback} [callback] this will be called after executing this method. The first parameter will contain null and the second one will contain a reference to this object.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.writeFile = function(file, options, callback) {
 if (typeof options === 'function') (callback = options), (options = {});
 options = options || {};
 return executeLegacyOperation(this.db.s.topology, writeFile, [this, file, options, callback], {
 skipSessions: true
 });
};
var writeFile = function(self, file, options, callback) {
 if (typeof file === 'string') {
 fs.open(file, 'r', function(err, fd) {
 if (err) return callback(err);
 self.writeFile(fd, callback);
 });
 return;
 }
 self.open(function(err, self) {
 if (err) return callback(err, self);
 fs.fstat(file, function(err, stats) {
 if (err) return callback(err, self);
 var offset = 0;
 var index = 0;
 // Write a chunk
 var writeChunk = function() {
 // Allocate the buffer
 var _buffer = Buffer.alloc(self.chunkSize);
 // Read the file
 fs.read(file, _buffer, 0, _buffer.length, offset, function(err, bytesRead, data) {
 if (err) return callback(err, self);
 offset = offset + bytesRead;
 // Create a new chunk for the data
 var chunk = new Chunk(self, { n: index++ }, self.writeConcern);
 chunk.write(data.slice(0, bytesRead), function(err, chunk) {
 if (err) return callback(err, self);
 chunk.save({}, function(err) {
 if (err) return callback(err, self);
 self.position = self.position + bytesRead;
 // Point to current chunk
 self.currentChunk = chunk;
 if (offset>= stats.size) {
 fs.close(file, function(err) {
 if (err) return callback(err);
 self.close(function(err) {
 if (err) return callback(err, self);
 return callback(null, self);
 });
 });
 } else {
 return process.nextTick(writeChunk);
 }
 });
 });
 });
 };
 // Process the first write
 process.nextTick(writeChunk);
 });
 });
};
/**
 * Saves this file to the database. This will overwrite the old entry if it
 * already exists. This will work properly only if mode was initialized to
 * "w" or "w+".
 *
 * @method
 * @param {object} [options] Optional settings
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~resultCallback} [callback] this will be called after executing this method. The first parameter will contain null and the second one will contain a reference to this object.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.close = function(options, callback) {
 if (typeof options === 'function') (callback = options), (options = {});
 options = options || {};
 return executeLegacyOperation(this.db.s.topology, close, [this, options, callback], {
 skipSessions: true
 });
};
var close = function(self, options, callback) {
 if (self.mode[0] === 'w') {
 // Set up options
 options = Object.assign({}, self.writeConcern, options);
 if (self.currentChunk != null && self.currentChunk.position> 0) {
 self.currentChunk.save({}, function(err) {
 if (err && typeof callback === 'function') return callback(err);
 self.collection(function(err, files) {
 if (err && typeof callback === 'function') return callback(err);
 // Build the mongo object
 if (self.uploadDate != null) {
 buildMongoObject(self, function(err, mongoObject) {
 if (err) {
 if (typeof callback === 'function') return callback(err);
 else throw err;
 }
 files.save(mongoObject, options, function(err) {
 if (typeof callback === 'function') callback(err, mongoObject);
 });
 });
 } else {
 self.uploadDate = new Date();
 buildMongoObject(self, function(err, mongoObject) {
 if (err) {
 if (typeof callback === 'function') return callback(err);
 else throw err;
 }
 files.save(mongoObject, options, function(err) {
 if (typeof callback === 'function') callback(err, mongoObject);
 });
 });
 }
 });
 });
 } else {
 self.collection(function(err, files) {
 if (err && typeof callback === 'function') return callback(err);
 self.uploadDate = new Date();
 buildMongoObject(self, function(err, mongoObject) {
 if (err) {
 if (typeof callback === 'function') return callback(err);
 else throw err;
 }
 files.save(mongoObject, options, function(err) {
 if (typeof callback === 'function') callback(err, mongoObject);
 });
 });
 });
 }
 } else if (self.mode[0] === 'r') {
 if (typeof callback === 'function') callback(null, null);
 } else {
 if (typeof callback === 'function')
 callback(MongoError.create({ message: f('Illegal mode %s', self.mode), driver: true }));
 }
};
/**
 * The collection callback format.
 * @callback GridStore~collectionCallback
 * @param {MongoError} error An error instance representing the error during the execution.
 * @param {Collection} collection The collection from the command execution.
 */
/**
 * Retrieve this file's chunks collection.
 *
 * @method
 * @param {GridStore~collectionCallback} callback the command callback.
 * @return {Collection}
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.chunkCollection = function(callback) {
 if (typeof callback === 'function') return this.db.collection(this.root + '.chunks', callback);
 return this.db.collection(this.root + '.chunks');
};
/**
 * Deletes all the chunks of this file in the database.
 *
 * @method
 * @param {object} [options] Optional settings
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~resultCallback} [callback] the command callback.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.unlink = function(options, callback) {
 if (typeof options === 'function') (callback = options), (options = {});
 options = options || {};
 return executeLegacyOperation(this.db.s.topology, unlink, [this, options, callback], {
 skipSessions: true
 });
};
var unlink = function(self, options, callback) {
 deleteChunks(self, function(err) {
 if (err !== null) {
 err.message = 'at deleteChunks: ' + err.message;
 return callback(err);
 }
 self.collection(function(err, collection) {
 if (err !== null) {
 err.message = 'at collection: ' + err.message;
 return callback(err);
 }
 collection.remove({ _id: self.fileId }, self.writeConcern, function(err) {
 callback(err, self);
 });
 });
 });
};
/**
 * Retrieves the file collection associated with this object.
 *
 * @method
 * @param {GridStore~collectionCallback} callback the command callback.
 * @return {Collection}
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.collection = function(callback) {
 if (typeof callback === 'function') this.db.collection(this.root + '.files', callback);
 return this.db.collection(this.root + '.files');
};
/**
 * The readlines callback format.
 * @callback GridStore~readlinesCallback
 * @param {MongoError} error An error instance representing the error during the execution.
 * @param {string[]} strings The array of strings returned.
 */
/**
 * Read the entire file as a list of strings splitting by the provided separator.
 *
 * @method
 * @param {string} [separator] The character to be recognized as the newline separator.
 * @param {object} [options] Optional settings
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~readlinesCallback} [callback] the command callback.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.readlines = function(separator, options, callback) {
 var args = Array.prototype.slice.call(arguments, 0);
 callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
 separator = args.length ? args.shift() : '\n';
 separator = separator || '\n';
 options = args.length ? args.shift() : {};
 return executeLegacyOperation(
 this.db.s.topology,
 readlines,
 [this, separator, options, callback],
 { skipSessions: true }
 );
};
var readlines = function(self, separator, options, callback) {
 self.read(function(err, data) {
 if (err) return callback(err);
 var items = data.toString().split(separator);
 items = items.length> 0 ? items.splice(0, items.length - 1) : [];
 for (var i = 0; i < items.length; i++) {
 items[i] = items[i] + separator;
 }
 callback(null, items);
 });
};
/**
 * Deletes all the chunks of this file in the database if mode was set to "w" or
 * "w+" and resets the read/write head to the initial position.
 *
 * @method
 * @param {object} [options] Optional settings
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~resultCallback} [callback] this will be called after executing this method. The first parameter will contain null and the second one will contain a reference to this object.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.rewind = function(options, callback) {
 if (typeof options === 'function') (callback = options), (options = {});
 options = options || {};
 return executeLegacyOperation(this.db.s.topology, rewind, [this, options, callback], {
 skipSessions: true
 });
};
var rewind = function(self, options, callback) {
 if (self.currentChunk.chunkNumber !== 0) {
 if (self.mode[0] === 'w') {
 deleteChunks(self, function(err) {
 if (err) return callback(err);
 self.currentChunk = new Chunk(self, { n: 0 }, self.writeConcern);
 self.position = 0;
 callback(null, self);
 });
 } else {
 self.currentChunk(0, function(err, chunk) {
 if (err) return callback(err);
 self.currentChunk = chunk;
 self.currentChunk.rewind();
 self.position = 0;
 callback(null, self);
 });
 }
 } else {
 self.currentChunk.rewind();
 self.position = 0;
 callback(null, self);
 }
};
/**
 * The read callback format.
 * @callback GridStore~readCallback
 * @param {MongoError} error An error instance representing the error during the execution.
 * @param {Buffer} data The data read from the GridStore object
 */
/**
 * Retrieves the contents of this file and advances the read/write head. Works with Buffers only.
 *
 * There are 3 signatures for this method:
 *
 * (callback)
 * (length, callback)
 * (length, buffer, callback)
 *
 * @method
 * @param {number} [length] the number of characters to read. Reads all the characters from the read/write head to the EOF if not specified.
 * @param {(string|Buffer)} [buffer] a string to hold temporary data. This is used for storing the string data read so far when recursively calling this method.
 * @param {object} [options] Optional settings
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~readCallback} [callback] the command callback.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.read = function(length, buffer, options, callback) {
 var args = Array.prototype.slice.call(arguments, 0);
 callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
 length = args.length ? args.shift() : null;
 buffer = args.length ? args.shift() : null;
 options = args.length ? args.shift() : {};
 return executeLegacyOperation(
 this.db.s.topology,
 read,
 [this, length, buffer, options, callback],
 { skipSessions: true }
 );
};
var read = function(self, length, buffer, options, callback) {
 // The data is a c-terminated string and thus the length - 1
 var finalLength = length == null ? self.length - self.position : length;
 var finalBuffer = buffer == null ? Buffer.alloc(finalLength) : buffer;
 // Add a index to buffer to keep track of writing position or apply current index
 finalBuffer._index = buffer != null && buffer._index != null ? buffer._index : 0;
 if (self.currentChunk.length() - self.currentChunk.position + finalBuffer._index>= finalLength) {
 var slice = self.currentChunk.readSlice(finalLength - finalBuffer._index);
 // Copy content to final buffer
 slice.copy(finalBuffer, finalBuffer._index);
 // Update internal position
 self.position = self.position + finalBuffer.length;
 // Check if we don't have a file at all
 if (finalLength === 0 && finalBuffer.length === 0)
 return callback(MongoError.create({ message: 'File does not exist', driver: true }), null);
 // Else return data
 return callback(null, finalBuffer);
 }
 // Read the next chunk
 slice = self.currentChunk.readSlice(self.currentChunk.length() - self.currentChunk.position);
 // Copy content to final buffer
 slice.copy(finalBuffer, finalBuffer._index);
 // Update index position
 finalBuffer._index += slice.length;
 // Load next chunk and read more
 nthChunk(self, self.currentChunk.chunkNumber + 1, function(err, chunk) {
 if (err) return callback(err);
 if (chunk.length()> 0) {
 self.currentChunk = chunk;
 self.read(length, finalBuffer, callback);
 } else {
 if (finalBuffer._index> 0) {
 callback(null, finalBuffer);
 } else {
 callback(
 MongoError.create({
 message: 'no chunks found for file, possibly corrupt',
 driver: true
 }),
 null
 );
 }
 }
 });
};
/**
 * The tell callback format.
 * @callback GridStore~tellCallback
 * @param {MongoError} error An error instance representing the error during the execution.
 * @param {number} position The current read position in the GridStore.
 */
/**
 * Retrieves the position of the read/write head of this file.
 *
 * @method
 * @param {number} [length] the number of characters to read. Reads all the characters from the read/write head to the EOF if not specified.
 * @param {(string|Buffer)} [buffer] a string to hold temporary data. This is used for storing the string data read so far when recursively calling this method.
 * @param {object} [options] Optional settings
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~tellCallback} [callback] the command callback.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.tell = function(callback) {
 var self = this;
 // We provided a callback leg
 if (typeof callback === 'function') return callback(null, this.position);
 // Return promise
 return new self.promiseLibrary(function(resolve) {
 resolve(self.position);
 });
};
/**
 * The tell callback format.
 * @callback GridStore~gridStoreCallback
 * @param {MongoError} error An error instance representing the error during the execution.
 * @param {GridStore} gridStore The gridStore.
 */
/**
 * Moves the read/write head to a new location.
 *
 * There are 3 signatures for this method
 *
 * Seek Location Modes
 * - **GridStore.IO_SEEK_SET**, **(default)** set the position from the start of the file.
 * - **GridStore.IO_SEEK_CUR**, set the position from the current position in the file.
 * - **GridStore.IO_SEEK_END**, set the position from the end of the file.
 *
 * @method
 * @param {number} [position] the position to seek to
 * @param {number} [seekLocation] seek mode. Use one of the Seek Location modes.
 * @param {object} [options] Optional settings
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~gridStoreCallback} [callback] the command callback.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.prototype.seek = function(position, seekLocation, options, callback) {
 var args = Array.prototype.slice.call(arguments, 1);
 callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
 seekLocation = args.length ? args.shift() : null;
 options = args.length ? args.shift() : {};
 return executeLegacyOperation(
 this.db.s.topology,
 seek,
 [this, position, seekLocation, options, callback],
 { skipSessions: true }
 );
};
var seek = function(self, position, seekLocation, options, callback) {
 // Seek only supports read mode
 if (self.mode !== 'r') {
 return callback(
 MongoError.create({ message: 'seek is only supported for mode r', driver: true })
 );
 }
 var seekLocationFinal = seekLocation == null ? GridStore.IO_SEEK_SET : seekLocation;
 var finalPosition = position;
 var targetPosition = 0;
 // Calculate the position
 if (seekLocationFinal === GridStore.IO_SEEK_CUR) {
 targetPosition = self.position + finalPosition;
 } else if (seekLocationFinal === GridStore.IO_SEEK_END) {
 targetPosition = self.length + finalPosition;
 } else {
 targetPosition = finalPosition;
 }
 // Get the chunk
 var newChunkNumber = Math.floor(targetPosition / self.chunkSize);
 var seekChunk = function() {
 nthChunk(self, newChunkNumber, function(err, chunk) {
 if (err) return callback(err, null);
 if (chunk == null) return callback(new Error('no chunk found'));
 // Set the current chunk
 self.currentChunk = chunk;
 self.position = targetPosition;
 self.currentChunk.position = self.position % self.chunkSize;
 callback(err, self);
 });
 };
 seekChunk();
};
/**
 * @ignore
 */
var _open = function(self, options, callback) {
 var collection = self.collection();
 // Create the query
 var query =
 self.referenceBy === REFERENCE_BY_ID ? { _id: self.fileId } : { filename: self.filename };
 query = null == self.fileId && self.filename == null ? null : query;
 options.readPreference = self.readPreference;
 // Fetch the chunks
 if (query != null) {
 collection.findOne(query, options, function(err, doc) {
 if (err) {
 return error(err);
 }
 // Check if the collection for the files exists otherwise prepare the new one
 if (doc != null) {
 self.fileId = doc._id;
 // Prefer a new filename over the existing one if this is a write
 self.filename =
 self.mode === 'r' || self.filename === undefined ? doc.filename : self.filename;
 self.contentType = doc.contentType;
 self.internalChunkSize = doc.chunkSize;
 self.uploadDate = doc.uploadDate;
 self.aliases = doc.aliases;
 self.length = doc.length;
 self.metadata = doc.metadata;
 self.internalMd5 = doc.md5;
 } else if (self.mode !== 'r') {
 self.fileId = self.fileId == null ? new ObjectID() : self.fileId;
 self.contentType = GridStore.DEFAULT_CONTENT_TYPE;
 self.internalChunkSize =
 self.internalChunkSize == null ? Chunk.DEFAULT_CHUNK_SIZE : self.internalChunkSize;
 self.length = 0;
 } else {
 self.length = 0;
 var txtId = self.fileId._bsontype === 'ObjectID' ? self.fileId.toHexString() : self.fileId;
 return error(
 MongoError.create({
 message: f(
 'file with id %s not opened for writing',
 self.referenceBy === REFERENCE_BY_ID ? txtId : self.filename
 ),
 driver: true
 }),
 self
 );
 }
 // Process the mode of the object
 if (self.mode === 'r') {
 nthChunk(self, 0, options, function(err, chunk) {
 if (err) return error(err);
 self.currentChunk = chunk;
 self.position = 0;
 callback(null, self);
 });
 } else if (self.mode === 'w' && doc) {
 // Delete any existing chunks
 deleteChunks(self, options, function(err) {
 if (err) return error(err);
 self.currentChunk = new Chunk(self, { n: 0 }, self.writeConcern);
 self.contentType =
 self.options['content_type'] == null ? self.contentType : self.options['content_type'];
 self.internalChunkSize =
 self.options['chunk_size'] == null
 ? self.internalChunkSize
 : self.options['chunk_size'];
 self.metadata =
 self.options['metadata'] == null ? self.metadata : self.options['metadata'];
 self.aliases = self.options['aliases'] == null ? self.aliases : self.options['aliases'];
 self.position = 0;
 callback(null, self);
 });
 } else if (self.mode === 'w') {
 self.currentChunk = new Chunk(self, { n: 0 }, self.writeConcern);
 self.contentType =
 self.options['content_type'] == null ? self.contentType : self.options['content_type'];
 self.internalChunkSize =
 self.options['chunk_size'] == null ? self.internalChunkSize : self.options['chunk_size'];
 self.metadata = self.options['metadata'] == null ? self.metadata : self.options['metadata'];
 self.aliases = self.options['aliases'] == null ? self.aliases : self.options['aliases'];
 self.position = 0;
 callback(null, self);
 } else if (self.mode === 'w+') {
 nthChunk(self, lastChunkNumber(self), options, function(err, chunk) {
 if (err) return error(err);
 // Set the current chunk
 self.currentChunk = chunk == null ? new Chunk(self, { n: 0 }, self.writeConcern) : chunk;
 self.currentChunk.position = self.currentChunk.data.length();
 self.metadata =
 self.options['metadata'] == null ? self.metadata : self.options['metadata'];
 self.aliases = self.options['aliases'] == null ? self.aliases : self.options['aliases'];
 self.position = self.length;
 callback(null, self);
 });
 }
 });
 } else {
 // Write only mode
 self.fileId = null == self.fileId ? new ObjectID() : self.fileId;
 self.contentType = GridStore.DEFAULT_CONTENT_TYPE;
 self.internalChunkSize =
 self.internalChunkSize == null ? Chunk.DEFAULT_CHUNK_SIZE : self.internalChunkSize;
 self.length = 0;
 // No file exists set up write mode
 if (self.mode === 'w') {
 // Delete any existing chunks
 deleteChunks(self, options, function(err) {
 if (err) return error(err);
 self.currentChunk = new Chunk(self, { n: 0 }, self.writeConcern);
 self.contentType =
 self.options['content_type'] == null ? self.contentType : self.options['content_type'];
 self.internalChunkSize =
 self.options['chunk_size'] == null ? self.internalChunkSize : self.options['chunk_size'];
 self.metadata = self.options['metadata'] == null ? self.metadata : self.options['metadata'];
 self.aliases = self.options['aliases'] == null ? self.aliases : self.options['aliases'];
 self.position = 0;
 callback(null, self);
 });
 } else if (self.mode === 'w+') {
 nthChunk(self, lastChunkNumber(self), options, function(err, chunk) {
 if (err) return error(err);
 // Set the current chunk
 self.currentChunk = chunk == null ? new Chunk(self, { n: 0 }, self.writeConcern) : chunk;
 self.currentChunk.position = self.currentChunk.data.length();
 self.metadata = self.options['metadata'] == null ? self.metadata : self.options['metadata'];
 self.aliases = self.options['aliases'] == null ? self.aliases : self.options['aliases'];
 self.position = self.length;
 callback(null, self);
 });
 }
 }
 // only pass error to callback once
 function error(err) {
 if (error.err) return;
 callback((error.err = err));
 }
};
/**
 * @ignore
 */
var writeBuffer = function(self, buffer, close, callback) {
 if (typeof close === 'function') {
 callback = close;
 close = null;
 }
 var finalClose = typeof close === 'boolean' ? close : false;
 if (self.mode !== 'w') {
 callback(
 MongoError.create({
 message: f(
 'file with id %s not opened for writing',
 self.referenceBy === REFERENCE_BY_ID ? self.referenceBy : self.filename
 ),
 driver: true
 }),
 null
 );
 } else {
 if (self.currentChunk.position + buffer.length>= self.chunkSize) {
 // Write out the current Chunk and then keep writing until we have less data left than a chunkSize left
 // to a new chunk (recursively)
 var previousChunkNumber = self.currentChunk.chunkNumber;
 var leftOverDataSize = self.chunkSize - self.currentChunk.position;
 var firstChunkData = buffer.slice(0, leftOverDataSize);
 var leftOverData = buffer.slice(leftOverDataSize);
 // A list of chunks to write out
 var chunksToWrite = [self.currentChunk.write(firstChunkData)];
 // If we have more data left than the chunk size let's keep writing new chunks
 while (leftOverData.length>= self.chunkSize) {
 // Create a new chunk and write to it
 var newChunk = new Chunk(self, { n: previousChunkNumber + 1 }, self.writeConcern);
 firstChunkData = leftOverData.slice(0, self.chunkSize);
 leftOverData = leftOverData.slice(self.chunkSize);
 // Update chunk number
 previousChunkNumber = previousChunkNumber + 1;
 // Write data
 newChunk.write(firstChunkData);
 // Push chunk to save list
 chunksToWrite.push(newChunk);
 }
 // Set current chunk with remaining data
 self.currentChunk = new Chunk(self, { n: previousChunkNumber + 1 }, self.writeConcern);
 // If we have left over data write it
 if (leftOverData.length> 0) self.currentChunk.write(leftOverData);
 // Update the position for the gridstore
 self.position = self.position + buffer.length;
 // Total number of chunks to write
 var numberOfChunksToWrite = chunksToWrite.length;
 for (var i = 0; i < chunksToWrite.length; i++) {
 chunksToWrite[i].save({}, function(err) {
 if (err) return callback(err);
 numberOfChunksToWrite = numberOfChunksToWrite - 1;
 if (numberOfChunksToWrite <= 0) {
 // We care closing the file before returning
 if (finalClose) {
 return self.close(function(err) {
 callback(err, self);
 });
 }
 // Return normally
 return callback(null, self);
 }
 });
 }
 } else {
 // Update the position for the gridstore
 self.position = self.position + buffer.length;
 // We have less data than the chunk size just write it and callback
 self.currentChunk.write(buffer);
 // We care closing the file before returning
 if (finalClose) {
 return self.close(function(err) {
 callback(err, self);
 });
 }
 // Return normally
 return callback(null, self);
 }
 }
};
/**
 * Creates a mongoDB object representation of this object.
 *
 * <pre><code>
 * {
 * '_id' : , // {number} id for this file
 * 'filename' : , // {string} name for this file
 * 'contentType' : , // {string} mime type for this file
 * 'length' : , // {number} size of this file?
 * 'chunksize' : , // {number} chunk size used by this file
 * 'uploadDate' : , // {Date}
 * 'aliases' : , // {array of string}
 * 'metadata' : , // {string}
 * }
 * </code></pre>
 *
 * @ignore
 */
var buildMongoObject = function(self, callback) {
 // Calcuate the length
 var mongoObject = {
 _id: self.fileId,
 filename: self.filename,
 contentType: self.contentType,
 length: self.position ? self.position : 0,
 chunkSize: self.chunkSize,
 uploadDate: self.uploadDate,
 aliases: self.aliases,
 metadata: self.metadata
 };
 var md5Command = { filemd5: self.fileId, root: self.root };
 self.db.command(md5Command, function(err, results) {
 if (err) return callback(err);
 mongoObject.md5 = results.md5;
 callback(null, mongoObject);
 });
};
/**
 * Gets the nth chunk of this file.
 * @ignore
 */
var nthChunk = function(self, chunkNumber, options, callback) {
 if (typeof options === 'function') {
 callback = options;
 options = {};
 }
 options = options || self.writeConcern;
 options.readPreference = self.readPreference;
 // Get the nth chunk
 self
 .chunkCollection()
 .findOne({ files_id: self.fileId, n: chunkNumber }, options, function(err, chunk) {
 if (err) return callback(err);
 var finalChunk = chunk == null ? {} : chunk;
 callback(null, new Chunk(self, finalChunk, self.writeConcern));
 });
};
/**
 * @ignore
 */
var lastChunkNumber = function(self) {
 return Math.floor((self.length ? self.length - 1 : 0) / self.chunkSize);
};
/**
 * Deletes all the chunks of this file in the database.
 *
 * @ignore
 */
var deleteChunks = function(self, options, callback) {
 if (typeof options === 'function') {
 callback = options;
 options = {};
 }
 options = options || self.writeConcern;
 if (self.fileId != null) {
 self.chunkCollection().remove({ files_id: self.fileId }, options, function(err) {
 if (err) return callback(err, false);
 callback(null, true);
 });
 } else {
 callback(null, true);
 }
};
/**
 * The collection to be used for holding the files and chunks collection.
 *
 * @classconstant DEFAULT_ROOT_COLLECTION
 */
GridStore.DEFAULT_ROOT_COLLECTION = 'fs';
/**
 * Default file mime type
 *
 * @classconstant DEFAULT_CONTENT_TYPE
 */
GridStore.DEFAULT_CONTENT_TYPE = 'binary/octet-stream';
/**
 * Seek mode where the given length is absolute.
 *
 * @classconstant IO_SEEK_SET
 */
GridStore.IO_SEEK_SET = 0;
/**
 * Seek mode where the given length is an offset to the current read/write head.
 *
 * @classconstant IO_SEEK_CUR
 */
GridStore.IO_SEEK_CUR = 1;
/**
 * Seek mode where the given length is an offset to the end of the file.
 *
 * @classconstant IO_SEEK_END
 */
GridStore.IO_SEEK_END = 2;
/**
 * Checks if a file exists in the database.
 *
 * @method
 * @static
 * @param {Db} db the database to query.
 * @param {string} name The name of the file to look for.
 * @param {string} [rootCollection] The root collection that holds the files and chunks collection. Defaults to **{GridStore.DEFAULT_ROOT_COLLECTION}**.
 * @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.promiseLibrary] A Promise library class the application wishes to use such as Bluebird, must be ES6 compatible
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~resultCallback} [callback] result from exists.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.exist = function(db, fileIdObject, rootCollection, options, callback) {
 var args = Array.prototype.slice.call(arguments, 2);
 callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
 rootCollection = args.length ? args.shift() : null;
 options = args.length ? args.shift() : {};
 options = options || {};
 return executeLegacyOperation(
 db.s.topology,
 exists,
 [db, fileIdObject, rootCollection, options, callback],
 { skipSessions: true }
 );
};
var exists = function(db, fileIdObject, rootCollection, options, callback) {
 // Establish read preference
 var readPreference = options.readPreference || ReadPreference.PRIMARY;
 // Fetch collection
 var rootCollectionFinal =
 rootCollection != null ? rootCollection : GridStore.DEFAULT_ROOT_COLLECTION;
 db.collection(rootCollectionFinal + '.files', function(err, collection) {
 if (err) return callback(err);
 // Build query
 var query =
 typeof fileIdObject === 'string' ||
 Object.prototype.toString.call(fileIdObject) === '[object RegExp]'
 ? { filename: fileIdObject }
 : { _id: fileIdObject }; // Attempt to locate file
 // We have a specific query
 if (
 fileIdObject != null &&
 typeof fileIdObject === 'object' &&
 Object.prototype.toString.call(fileIdObject) !== '[object RegExp]'
 ) {
 query = fileIdObject;
 }
 // Check if the entry exists
 collection.findOne(query, { readPreference: readPreference }, function(err, item) {
 if (err) return callback(err);
 callback(null, item == null ? false : true);
 });
 });
};
/**
 * Gets the list of files stored in the GridFS.
 *
 * @method
 * @static
 * @param {Db} db the database to query.
 * @param {string} [rootCollection] The root collection that holds the files and chunks collection. Defaults to **{GridStore.DEFAULT_ROOT_COLLECTION}**.
 * @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.promiseLibrary] A Promise library class the application wishes to use such as Bluebird, must be ES6 compatible
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~resultCallback} [callback] result from exists.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.list = function(db, rootCollection, options, callback) {
 var args = Array.prototype.slice.call(arguments, 1);
 callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
 rootCollection = args.length ? args.shift() : null;
 options = args.length ? args.shift() : {};
 options = options || {};
 return executeLegacyOperation(db.s.topology, list, [db, rootCollection, options, callback], {
 skipSessions: true
 });
};
var list = function(db, rootCollection, options, callback) {
 // Ensure we have correct values
 if (rootCollection != null && typeof rootCollection === 'object') {
 options = rootCollection;
 rootCollection = null;
 }
 // Establish read preference
 var readPreference = options.readPreference || ReadPreference.primary;
 // Check if we are returning by id not filename
 var byId = options['id'] != null ? options['id'] : false;
 // Fetch item
 var rootCollectionFinal =
 rootCollection != null ? rootCollection : GridStore.DEFAULT_ROOT_COLLECTION;
 var items = [];
 db.collection(rootCollectionFinal + '.files', function(err, collection) {
 if (err) return callback(err);
 collection.find({}, { readPreference: readPreference }, function(err, cursor) {
 if (err) return callback(err);
 cursor.each(function(err, item) {
 if (item != null) {
 items.push(byId ? item._id : item.filename);
 } else {
 callback(err, items);
 }
 });
 });
 });
};
/**
 * Reads the contents of a file.
 *
 * This method has the following signatures
 *
 * (db, name, callback)
 * (db, name, length, callback)
 * (db, name, length, offset, callback)
 * (db, name, length, offset, options, callback)
 *
 * @method
 * @static
 * @param {Db} db the database to query.
 * @param {string} name The name of the file.
 * @param {number} [length] The size of data to read.
 * @param {number} [offset] The offset from the head of the file of which to start reading from.
 * @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.promiseLibrary] A Promise library class the application wishes to use such as Bluebird, must be ES6 compatible
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~readCallback} [callback] the command callback.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.read = function(db, name, length, offset, options, callback) {
 var args = Array.prototype.slice.call(arguments, 2);
 callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
 length = args.length ? args.shift() : null;
 offset = args.length ? args.shift() : null;
 options = args.length ? args.shift() : null;
 options = options || {};
 return executeLegacyOperation(
 db.s.topology,
 readStatic,
 [db, name, length, offset, options, callback],
 { skipSessions: true }
 );
};
var readStatic = function(db, name, length, offset, options, callback) {
 new GridStore(db, name, 'r', options).open(function(err, gridStore) {
 if (err) return callback(err);
 // Make sure we are not reading out of bounds
 if (offset && offset>= gridStore.length)
 return callback('offset larger than size of file', null);
 if (length && length> gridStore.length)
 return callback('length is larger than the size of the file', null);
 if (offset && length && offset + length> gridStore.length)
 return callback('offset and length is larger than the size of the file', null);
 if (offset != null) {
 gridStore.seek(offset, function(err, gridStore) {
 if (err) return callback(err);
 gridStore.read(length, callback);
 });
 } else {
 gridStore.read(length, callback);
 }
 });
};
/**
 * Read the entire file as a list of strings splitting by the provided separator.
 *
 * @method
 * @static
 * @param {Db} db the database to query.
 * @param {(String|object)} name the name of the file.
 * @param {string} [separator] The character to be recognized as the newline separator.
 * @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.promiseLibrary] A Promise library class the application wishes to use such as Bluebird, must be ES6 compatible
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~readlinesCallback} [callback] the command callback.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.readlines = function(db, name, separator, options, callback) {
 var args = Array.prototype.slice.call(arguments, 2);
 callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
 separator = args.length ? args.shift() : null;
 options = args.length ? args.shift() : null;
 options = options || {};
 return executeLegacyOperation(
 db.s.topology,
 readlinesStatic,
 [db, name, separator, options, callback],
 { skipSessions: true }
 );
};
var readlinesStatic = function(db, name, separator, options, callback) {
 var finalSeperator = separator == null ? '\n' : separator;
 new GridStore(db, name, 'r', options).open(function(err, gridStore) {
 if (err) return callback(err);
 gridStore.readlines(finalSeperator, callback);
 });
};
/**
 * Deletes the chunks and metadata information of a file from GridFS.
 *
 * @method
 * @static
 * @param {Db} db The database to query.
 * @param {(string|array)} names The name/names of the files to delete.
 * @param {object} [options] Optional settings.
 * @param {object} [options.promiseLibrary] A Promise library class the application wishes to use such as Bluebird, must be ES6 compatible
 * @param {ClientSession} [options.session] optional session to use for this operation
 * @param {GridStore~resultCallback} [callback] the command callback.
 * @return {Promise} returns Promise if no callback passed
 * @deprecated Use GridFSBucket API instead
 */
GridStore.unlink = function(db, names, options, callback) {
 var args = Array.prototype.slice.call(arguments, 2);
 callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
 options = args.length ? args.shift() : {};
 options = options || {};
 return executeLegacyOperation(db.s.topology, unlinkStatic, [this, db, names, options, callback], {
 skipSessions: true
 });
};
var unlinkStatic = function(self, db, names, options, callback) {
 // Get the write concern
 var writeConcern = _getWriteConcern(db, options);
 // List of names
 if (names.constructor === Array) {
 var tc = 0;
 for (var i = 0; i < names.length; i++) {
 ++tc;
 GridStore.unlink(db, names[i], options, function() {
 if (--tc === 0) {
 callback(null, self);
 }
 });
 }
 } else {
 new GridStore(db, names, 'w', options).open(function(err, gridStore) {
 if (err) return callback(err);
 deleteChunks(gridStore, function(err) {
 if (err) return callback(err);
 gridStore.collection(function(err, collection) {
 if (err) return callback(err);
 collection.remove({ _id: gridStore.fileId }, writeConcern, function(err) {
 callback(err, self);
 });
 });
 });
 });
 }
};
/**
 * @ignore
 */
var _writeNormal = function(self, data, close, options, callback) {
 // If we have a buffer write it using the writeBuffer method
 if (Buffer.isBuffer(data)) {
 return writeBuffer(self, data, close, callback);
 } else {
 return writeBuffer(self, Buffer.from(data, 'binary'), close, callback);
 }
};
/**
 * @ignore
 */
var _setWriteConcernHash = function(options) {
 var finalOptions = {};
 if (options.w != null) finalOptions.w = options.w;
 if (options.journal === true) finalOptions.j = options.journal;
 if (options.j === true) finalOptions.j = options.j;
 if (options.fsync === true) finalOptions.fsync = options.fsync;
 if (options.wtimeout != null) finalOptions.wtimeout = options.wtimeout;
 return finalOptions;
};
/**
 * @ignore
 */
var _getWriteConcern = function(self, options) {
 // Final options
 var finalOptions = { w: 1 };
 options = options || {};
 // Local options verification
 if (
 options.w != null ||
 typeof options.j === 'boolean' ||
 typeof options.journal === 'boolean' ||
 typeof options.fsync === 'boolean'
 ) {
 finalOptions = _setWriteConcernHash(options);
 } else if (options.safe != null && typeof options.safe === 'object') {
 finalOptions = _setWriteConcernHash(options.safe);
 } else if (typeof options.safe === 'boolean') {
 finalOptions = { w: options.safe ? 1 : 0 };
 } else if (
 self.options.w != null ||
 typeof self.options.j === 'boolean' ||
 typeof self.options.journal === 'boolean' ||
 typeof self.options.fsync === 'boolean'
 ) {
 finalOptions = _setWriteConcernHash(self.options);
 } else if (
 self.safe &&
 (self.safe.w != null ||
 typeof self.safe.j === 'boolean' ||
 typeof self.safe.journal === 'boolean' ||
 typeof self.safe.fsync === 'boolean')
 ) {
 finalOptions = _setWriteConcernHash(self.safe);
 } else if (typeof self.safe === 'boolean') {
 finalOptions = { w: self.safe ? 1 : 0 };
 }
 // Ensure we don't have an invalid combination of write concerns
 if (
 finalOptions.w < 1 &&
 (finalOptions.journal === true || finalOptions.j === true || finalOptions.fsync === true)
 )
 throw MongoError.create({
 message: 'No acknowledgement using w < 1 cannot be combined with journal:true or fsync:true',
 driver: true
 });
 // Return the options
 return finalOptions;
};
/**
 * Create a new GridStoreStream instance (INTERNAL TYPE, do not instantiate directly)
 *
 * @class
 * @extends external:Duplex
 * @return {GridStoreStream} a GridStoreStream instance.
 * @deprecated Use GridFSBucket API instead
 */
var GridStoreStream = function(gs) {
 // Initialize the duplex stream
 Duplex.call(this);
 // Get the gridstore
 this.gs = gs;
 // End called
 this.endCalled = false;
 // If we have a seek
 this.totalBytesToRead = this.gs.length - this.gs.position;
 this.seekPosition = this.gs.position;
};
//
// Inherit duplex
inherits(GridStoreStream, Duplex);
GridStoreStream.prototype._pipe = GridStoreStream.prototype.pipe;
// Set up override
GridStoreStream.prototype.pipe = function(destination) {
 var self = this;
 // Only open gridstore if not already open
 if (!self.gs.isOpen) {
 self.gs.open(function(err) {
 if (err) return self.emit('error', err);
 self.totalBytesToRead = self.gs.length - self.gs.position;
 self._pipe.apply(self, [destination]);
 });
 } else {
 self.totalBytesToRead = self.gs.length - self.gs.position;
 self._pipe.apply(self, [destination]);
 }
 return destination;
};
// Called by stream
GridStoreStream.prototype._read = function() {
 var self = this;
 var read = function() {
 // Read data
 self.gs.read(length, function(err, buffer) {
 if (err && !self.endCalled) return self.emit('error', err);
 // Stream is closed
 if (self.endCalled || buffer == null) return self.push(null);
 // Remove bytes read
 if (buffer.length <= self.totalBytesToRead) {
 self.totalBytesToRead = self.totalBytesToRead - buffer.length;
 self.push(buffer);
 } else if (buffer.length> self.totalBytesToRead) {
 self.totalBytesToRead = self.totalBytesToRead - buffer._index;
 self.push(buffer.slice(0, buffer._index));
 }
 // Finished reading
 if (self.totalBytesToRead <= 0) {
 self.endCalled = true;
 }
 });
 };
 // Set read length
 var length =
 self.gs.length < self.gs.chunkSize ? self.gs.length - self.seekPosition : self.gs.chunkSize;
 if (!self.gs.isOpen) {
 self.gs.open(function(err) {
 self.totalBytesToRead = self.gs.length - self.gs.position;
 if (err) return self.emit('error', err);
 read();
 });
 } else {
 read();
 }
};
GridStoreStream.prototype.destroy = function() {
 this.pause();
 this.endCalled = true;
 this.gs.close();
 this.emit('end');
};
GridStoreStream.prototype.write = function(chunk) {
 var self = this;
 if (self.endCalled)
 return self.emit(
 'error',
 MongoError.create({ message: 'attempting to write to stream after end called', driver: true })
 );
 // Do we have to open the gridstore
 if (!self.gs.isOpen) {
 self.gs.open(function() {
 self.gs.isOpen = true;
 self.gs.write(chunk, function() {
 process.nextTick(function() {
 self.emit('drain');
 });
 });
 });
 return false;
 } else {
 self.gs.write(chunk, function() {
 self.emit('drain');
 });
 return true;
 }
};
GridStoreStream.prototype.end = function(chunk, encoding, callback) {
 var self = this;
 var args = Array.prototype.slice.call(arguments, 0);
 callback = typeof args[args.length - 1] === 'function' ? args.pop() : undefined;
 chunk = args.length ? args.shift() : null;
 encoding = args.length ? args.shift() : null;
 self.endCalled = true;
 if (chunk) {
 self.gs.write(chunk, function() {
 self.gs.close(function() {
 if (typeof callback === 'function') callback();
 self.emit('end');
 });
 });
 }
 self.gs.close(function() {
 if (typeof callback === 'function') callback();
 self.emit('end');
 });
};
/**
 * The read() method pulls some data out of the internal buffer and returns it. If there is no data available, then it will return null.
 * @function external:Duplex#read
 * @param {number} size Optional argument to specify how much data to read.
 * @return {(String | Buffer | null)}
 */
/**
 * Call this function to cause the stream to return strings of the specified encoding instead of Buffer objects.
 * @function external:Duplex#setEncoding
 * @param {string} encoding The encoding to use.
 * @return {null}
 */
/**
 * This method will cause the readable stream to resume emitting data events.
 * @function external:Duplex#resume
 * @return {null}
 */
/**
 * This method will cause a stream in flowing-mode to stop emitting data events. Any data that becomes available will remain in the internal buffer.
 * @function external:Duplex#pause
 * @return {null}
 */
/**
 * This method pulls all the data out of a readable stream, and writes it to the supplied destination, automatically managing the flow so that the destination is not overwhelmed by a fast readable stream.
 * @function external:Duplex#pipe
 * @param {Writable} destination The destination for writing data
 * @param {object} [options] Pipe options
 * @return {null}
 */
/**
 * This method will remove the hooks set up for a previous pipe() call.
 * @function external:Duplex#unpipe
 * @param {Writable} [destination] The destination for writing data
 * @return {null}
 */
/**
 * This is useful in certain cases where a stream is being consumed by a parser, which needs to "un-consume" some data that it has optimistically pulled out of the source, so that the stream can be passed on to some other party.
 * @function external:Duplex#unshift
 * @param {(Buffer|string)} chunk Chunk of data to unshift onto the read queue.
 * @return {null}
 */
/**
 * Versions of Node prior to v0.10 had streams that did not implement the entire Streams API as it is today. (See "Compatibility" below for more information.)
 * @function external:Duplex#wrap
 * @param {Stream} stream An "old style" readable stream.
 * @return {null}
 */
/**
 * This method writes some data to the underlying system, and calls the supplied callback once the data has been fully handled.
 * @function external:Duplex#write
 * @param {(string|Buffer)} chunk The data to write
 * @param {string} encoding The encoding, if chunk is a String
 * @param {function} callback Callback for when this chunk of data is flushed
 * @return {boolean}
 */
/**
 * Call this method when no more data will be written to the stream. If supplied, the callback is attached as a listener on the finish event.
 * @function external:Duplex#end
 * @param {(string|Buffer)} chunk The data to write
 * @param {string} encoding The encoding, if chunk is a String
 * @param {function} callback Callback for when this chunk of data is flushed
 * @return {null}
 */
/**
 * GridStoreStream stream data event, fired for each document in the cursor.
 *
 * @event GridStoreStream#data
 * @type {object}
 */
/**
 * GridStoreStream stream end event
 *
 * @event GridStoreStream#end
 * @type {null}
 */
/**
 * GridStoreStream stream close event
 *
 * @event GridStoreStream#close
 * @type {null}
 */
/**
 * GridStoreStream stream readable event
 *
 * @event GridStoreStream#readable
 * @type {null}
 */
/**
 * GridStoreStream stream drain event
 *
 * @event GridStoreStream#drain
 * @type {null}
 */
/**
 * GridStoreStream stream finish event
 *
 * @event GridStoreStream#finish
 * @type {null}
 */
/**
 * GridStoreStream stream pipe event
 *
 * @event GridStoreStream#pipe
 * @type {null}
 */
/**
 * GridStoreStream stream unpipe event
 *
 * @event GridStoreStream#unpipe
 * @type {null}
 */
/**
 * GridStoreStream stream error event
 *
 * @event GridStoreStream#error
 * @type {null}
 */
/**
 * @ignore
 */
module.exports = GridStore;

AltStyle によって変換されたページ (->オリジナル) /