Mongoose


Mongoose()

Parameters

Mongoose constructor.

The exports object of the mongoose module is an instance of this class. Most apps will only use this one instance.

Example:

const mongoose = require('mongoose');
mongoose instanceof mongoose.Mongoose; // true

// Create a new Mongoose instance with its own `connect()`, `set()`, `model()`, etc.
const m = new mongoose.Mongoose();

Mongoose.prototype.Aggregate()

The Mongoose Aggregate constructor


Mongoose.prototype.CastError()

Parameters
  • type «String» The name of the type

  • value «Any» The value that failed to cast

  • path «String» The path a.b.c in the doc where this cast error occurred

  • [reason] «Error» The original error that was thrown

The Mongoose CastError constructor


Mongoose.prototype.Collection()

The Mongoose Collection constructor


Mongoose.prototype.Connection()

The Mongoose Connection constructor


Mongoose.prototype.Date

Type:
  • «property»

The Mongoose Date SchemaType.

Example:

const schema = new Schema({ test: Date });
schema.path('test') instanceof mongoose.Date; // true

Mongoose.prototype.Decimal128

Type:
  • «property»

The Mongoose Decimal128 SchemaType. Used for declaring paths in your schema that should be 128-bit decimal floating points. Do not use this to create a new Decimal128 instance, use mongoose.Types.Decimal128 instead.

Example:

const vehicleSchema = new Schema({ fuelLevel: mongoose.Decimal128 });

Mongoose.prototype.Document()

The Mongoose Document constructor.


Mongoose.prototype.DocumentProvider()

The Mongoose DocumentProvider constructor. Mongoose users should not have to use this directly


Mongoose.prototype.Error()

The MongooseError constructor.


Mongoose.prototype.Mixed

Type:
  • «property»

The Mongoose Mixed SchemaType. Used for declaring paths in your schema that Mongoose's change tracking, casting, and validation should ignore.

Example:

const schema = new Schema({ arbitrary: mongoose.Mixed });

Mongoose.prototype.Model()

The Mongoose Model constructor.


Mongoose.prototype.Mongoose()

The Mongoose constructor

The exports of the mongoose module is an instance of this class.

Example:

const mongoose = require('mongoose');
const mongoose2 = new mongoose.Mongoose();

Mongoose.prototype.Number

Type:
  • «property»

The Mongoose Number SchemaType. Used for declaring paths in your schema that Mongoose should cast to numbers.

Example:

const schema = new Schema({ num: mongoose.Number });
// Equivalent to:
const schema = new Schema({ num: 'number' });

Mongoose.prototype.ObjectId

Type:
  • «property»

The Mongoose ObjectId SchemaType. Used for declaring paths in your schema that should be MongoDB ObjectIds. Do not use this to create a new ObjectId instance, use mongoose.Types.ObjectId instead.

Example:

const childSchema = new Schema({ parentId: mongoose.ObjectId });

Mongoose.prototype.Promise

Type:
  • «property»

The Mongoose Promise constructor.


Mongoose.prototype.PromiseProvider()

Storage layer for mongoose promises


Mongoose.prototype.Query()

The Mongoose Query constructor.


Mongoose.prototype.STATES

Type:
  • «property»

Expose connection states for user-land


Mongoose.prototype.Schema()

The Mongoose Schema constructor

Example:

const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const CatSchema = new Schema(..);

Mongoose.prototype.SchemaType()

The Mongoose SchemaType constructor


Mongoose.prototype.SchemaTypeOptions()

The constructor used for schematype options


Mongoose.prototype.SchemaTypes

Type:
  • «property»

The various Mongoose SchemaTypes.

Note:

Alias of mongoose.Schema.Types for backwards compatibility.


Mongoose.prototype.Types

Type:
  • «property»

The various Mongoose Types.

Example:

const mongoose = require('mongoose');
const array = mongoose.Types.Array;

Types:

Using this exposed access to the ObjectId type, we can construct ids on demand.

const ObjectId = mongoose.Types.ObjectId;
const id1 = new ObjectId;

Mongoose.prototype.VirtualType()

The Mongoose VirtualType constructor


Mongoose.prototype.connect()

Parameters
  • uri(s) «String»
  • [options] «Object» passed down to the MongoDB driver's connect() function, except for 4 mongoose-specific options explained below.

    • [options.bufferCommands=true] «Boolean» Mongoose specific option. Set to false to disable buffering on all models associated with this connection.

    • [options.dbName] «String» The name of the database we want to use. If not provided, use database name from connection string.

    • [options.user] «String» username for authentication, equivalent to options.auth.user. Maintained for backwards compatibility.

    • [options.pass] «String» password for authentication, equivalent to options.auth.password. Maintained for backwards compatibility.

    • [options.poolSize=5] «Number» The maximum number of sockets the MongoDB driver will keep open for this connection. By default, poolSize is 5. Keep in mind that, as of MongoDB 3.4, MongoDB only allows one operation per socket at a time, so you may want to increase this if you find you have a few slow queries that are blocking faster queries from proceeding. See Slow Trains in MongoDB and Node.js.

    • [options.useUnifiedTopology=false] «Boolean» False by default. Set to true to opt in to the MongoDB driver's replica set and sharded cluster monitoring engine.

    • [options.serverSelectionTimeoutMS] «Number» If useUnifiedTopology = true, the MongoDB driver will try to find a server to send any given operation to, and keep retrying for serverSelectionTimeoutMS milliseconds before erroring out. If not set, the MongoDB driver defaults to using 30000 (30 seconds).

    • [options.heartbeatFrequencyMS] «Number» If useUnifiedTopology = true, the MongoDB driver sends a heartbeat every heartbeatFrequencyMS to check on the status of the connection. A heartbeat is subject to serverSelectionTimeoutMS, so the MongoDB driver will retry failed heartbeats for up to 30 seconds by default. Mongoose only emits a 'disconnected' event after a heartbeat has failed, so you may want to decrease this setting to reduce the time between when your server goes down and when Mongoose emits 'disconnected'. We recommend you do not set this setting below 1000, too many heartbeats can lead to performance degradation.

    • [options.autoIndex=true] «Boolean» Mongoose-specific option. Set to false to disable automatic index creation for all models associated with this connection.

    • [options.useNewUrlParser=false] «Boolean» False by default. Set to true to opt in to the MongoDB driver's new URL parser logic.

    • [options.useFindAndModify=true] «Boolean» True by default. Set to false to make findOneAndUpdate() and findOneAndRemove() use native findOneAndUpdate() rather than findAndModify().

    • [options.reconnectTries=30] «Number» If you're connected to a single server or mongos proxy (as opposed to a replica set), the MongoDB driver will try to reconnect every reconnectInterval milliseconds for reconnectTries times, and give up afterward. When the driver gives up, the mongoose connection emits a reconnectFailed event. This option does nothing for replica set connections.

    • [options.reconnectInterval=1000] «Number» See reconnectTries option above.

    • [options.bufferMaxEntries] «Number» This option does nothing if useUnifiedTopology is set. The MongoDB driver also has its own buffering mechanism that kicks in when the driver is disconnected. Set this option to 0 and set bufferCommands to false on your schemas if you want your database operations to fail immediately when the driver is not connected, as opposed to waiting for reconnection.

    • [options.connectTimeoutMS=30000] «Number» How long the MongoDB driver will wait before killing a socket due to inactivity during initial connection. Defaults to 30000. This option is passed transparently to Node.js' socket#setTimeout() function.

    • [options.socketTimeoutMS=30000] «Number» How long the MongoDB driver will wait before killing a socket due to inactivity after initial connection. A socket may be inactive because of either no activity or a long-running operation. This is set to 30000 by default, you should set this to 2-3x your longest running operation if you expect some of your database operations to run longer than 20 seconds. This option is passed to Node.js socket#setTimeout() function after the MongoDB driver successfully completes.

    • [options.family=0] «Number» Passed transparently to Node.js' dns.lookup() function. May be either 0, 4, or 6. 4 means use IPv4 only, 6 means use IPv6 only, 0 means try both.

  • [callback] «Function»
Returns:
  • «Promise» resolves to this if connection succeeded

Opens the default mongoose connection.

Example:

mongoose.connect('mongodb://user:pass@localhost:port/database');

// replica sets
const uri = 'mongodb://user:pass@localhost:port,anotherhost:port,yetanother:port/mydatabase';
mongoose.connect(uri);

// with options
mongoose.connect(uri, options);

// optional callback that gets fired when initial connection completed
const uri = 'mongodb://nonexistent.domain:27000';
mongoose.connect(uri, function(error) {
  // if error is truthy, the initial connection failed.
})

Mongoose.prototype.connection

Type:
  • «Connection»

The Mongoose module's default connection. Equivalent to mongoose.connections[0], see connections.

Example:

const mongoose = require('mongoose');
mongoose.connect(...);
mongoose.connection.on('error', cb);

This is the connection used by default for every model created using mongoose.model.

To create a new connection, use createConnection().


Mongoose.prototype.connections

Type:
  • «Array»

An array containing all connections associated with this Mongoose instance. By default, there is 1 connection. Calling createConnection() adds a connection to this array.

Example:

const mongoose = require('mongoose');
mongoose.connections.length; // 1, just the default connection
mongoose.connections[0] === mongoose.connection; // true

mongoose.createConnection('mongodb://localhost:27017/test');
mongoose.connections.length; // 2

Mongoose.prototype.createConnection()

Parameters
  • [uri] «String» a mongodb:// URI

  • [options] «Object» passed down to the MongoDB driver's connect() function, except for 4 mongoose-specific options explained below.

    • [options.bufferCommands=true] «Boolean» Mongoose specific option. Set to false to disable buffering on all models associated with this connection.

    • [options.dbName] «String» The name of the database we want to use. If not provided, use database name from connection string.

    • [options.user] «String» username for authentication, equivalent to options.auth.user. Maintained for backwards compatibility.

    • [options.pass] «String» password for authentication, equivalent to options.auth.password. Maintained for backwards compatibility.

    • [options.autoIndex=true] «Boolean» Mongoose-specific option. Set to false to disable automatic index creation for all models associated with this connection.

    • [options.useNewUrlParser=false] «Boolean» False by default. Set to true to make all connections set the useNewUrlParser option by default.

    • [options.useUnifiedTopology=false] «Boolean» False by default. Set to true to make all connections set the useUnifiedTopology option by default.

    • [options.useFindAndModify=true] «Boolean» True by default. Set to false to make findOneAndUpdate() and findOneAndRemove() use native findOneAndUpdate() rather than findAndModify().

    • [options.reconnectTries=30] «Number» If you're connected to a single server or mongos proxy (as opposed to a replica set), the MongoDB driver will try to reconnect every reconnectInterval milliseconds for reconnectTries times, and give up afterward. When the driver gives up, the mongoose connection emits a reconnectFailed event. This option does nothing for replica set connections.

    • [options.reconnectInterval=1000] «Number» See reconnectTries option above.

    • [options.poolSize=5] «Number» The maximum number of sockets the MongoDB driver will keep open for this connection. By default, poolSize is 5. Keep in mind that, as of MongoDB 3.4, MongoDB only allows one operation per socket at a time, so you may want to increase this if you find you have a few slow queries that are blocking faster queries from proceeding. See Slow Trains in MongoDB and Node.js.

    • [options.bufferMaxEntries] «Number» This option does nothing if useUnifiedTopology is set. The MongoDB driver also has its own buffering mechanism that kicks in when the driver is disconnected. Set this option to 0 and set bufferCommands to false on your schemas if you want your database operations to fail immediately when the driver is not connected, as opposed to waiting for reconnection.

    • [options.connectTimeoutMS=30000] «Number» How long the MongoDB driver will wait before killing a socket due to inactivity during initial connection. Defaults to 30000. This option is passed transparently to Node.js' socket#setTimeout() function.

    • [options.socketTimeoutMS=30000] «Number» How long the MongoDB driver will wait before killing a socket due to inactivity after initial connection. A socket may be inactive because of either no activity or a long-running operation. This is set to 30000 by default, you should set this to 2-3x your longest running operation if you expect some of your database operations to run longer than 20 seconds. This option is passed to Node.js socket#setTimeout() function after the MongoDB driver successfully completes.

    • [options.family=0] «Number» Passed transparently to Node.js' dns.lookup() function. May be either 0, 4, or 6. 4 means use IPv4 only, 6 means use IPv6 only, 0 means try both.

Returns:
  • «Connection» the created Connection object. Connections are thenable, so you can do await mongoose.createConnection()

Creates a Connection instance.

Each connection instance maps to a single database. This method is helpful when managing multiple db connections.

Options passed take precedence over options included in connection strings.

Example:

// with mongodb:// URI
db = mongoose.createConnection('mongodb://user:pass@localhost:port/database');

// and options
const opts = { db: { native_parser: true }}
db = mongoose.createConnection('mongodb://user:pass@localhost:port/database', opts);

// replica sets
db = mongoose.createConnection('mongodb://user:pass@localhost:port,anotherhost:port,yetanother:port/database');

// and options
const opts = { replset: { strategy: 'ping', rs_name: 'testSet' }}
db = mongoose.createConnection('mongodb://user:pass@localhost:port,anotherhost:port,yetanother:port/database', opts);

// and options
const opts = { server: { auto_reconnect: false }, user: 'username', pass: 'mypassword' }
db = mongoose.createConnection('localhost', 'database', port, opts)

// initialize now, connect later
db = mongoose.createConnection();
db.openUri('localhost', 'database', port, [opts]);

Mongoose.prototype.deleteModel()

Parameters
  • name «String|RegExp» if string, the name of the model to remove. If regexp, removes all models whose name matches the regexp.

Returns:
  • «Mongoose» this

Removes the model named name from the default connection, if it exists. You can use this function to clean up any models you created in your tests to prevent OverwriteModelErrors.

Equivalent to mongoose.connection.deleteModel(name).

Example:

mongoose.model('User', new Schema({ name: String }));
console.log(mongoose.model('User')); // Model object
mongoose.deleteModel('User');
console.log(mongoose.model('User')); // undefined

// Usually useful in a Mocha `afterEach()` hook
afterEach(function() {
  mongoose.deleteModel(/.+/); // Delete every model
});

Mongoose.prototype.disconnect()

Parameters
  • [callback] «Function» called after all connection close, or when first error occurred.

Returns:
  • «Promise» resolves when all connections are closed, or rejects with the first error that occurred.

Runs .close() on all connections in parallel.


Mongoose.prototype.driver

Type:
  • «property»

The underlying driver this Mongoose instance uses to communicate with the database. A driver is a Mongoose-specific interface that defines functions like find().


Mongoose.prototype.get()

Parameters
  • key «String»

Gets mongoose options

Example:

mongoose.get('test') // returns the 'test' value

Mongoose.prototype.isValidObjectId()

Returns true if Mongoose can cast the given value to an ObjectId, or false otherwise.

Example:

mongoose.isValidObjectId(new mongoose.Types.ObjectId()); // true
mongoose.isValidObjectId('0123456789ab'); // true
mongoose.isValidObjectId(6); // false

Mongoose.prototype.model()

Parameters
  • name «String|Function» model name or class extending Model

  • [schema] «Schema» the schema to use.

  • [collection] «String» name (optional, inferred from model name)

  • [skipInit] «Boolean» whether to skip initialization (defaults to false)

Returns:
  • «Model» The model associated with name. Mongoose will create the model if it doesn't already exist.

Defines a model or retrieves it.

Models defined on the mongoose instance are available to all connection created by the same mongoose instance.

If you call mongoose.model() with twice the same name but a different schema, you will get an OverwriteModelError. If you call mongoose.model() with the same name and same schema, you'll get the same schema back.

Example:

const mongoose = require('mongoose');

// define an Actor model with this mongoose instance
const schema = new Schema({ name: String });
mongoose.model('Actor', schema);

// create a new connection
const conn = mongoose.createConnection(..);

// create Actor model
const Actor = conn.model('Actor', schema);
conn.model('Actor') === Actor; // true
conn.model('Actor', schema) === Actor; // true, same schema
conn.model('Actor', schema, 'actors') === Actor; // true, same schema and collection name

// This throws an `OverwriteModelError` because the schema is different.
conn.model('Actor', new Schema({ name: String }));

When no collection argument is passed, Mongoose uses the model name. If you don't like this behavior, either pass a collection name, use mongoose.pluralize(), or set your schemas collection name option.

Example:

const schema = new Schema({ name: String }, { collection: 'actor' });

// or

schema.set('collection', 'actor');

// or

const collectionName = 'actor'
const M = mongoose.model('Actor', schema, collectionName)

Mongoose.prototype.modelNames()

Returns:
  • «Array»

Returns an array of model names created on this instance of Mongoose.

Note:

Does not include names of models created using connection.model().


Mongoose.prototype.mongo

Type:
  • «property»

The node-mongodb-native driver Mongoose uses.


Mongoose.prototype.mquery

Type:
  • «property»

The mquery query builder Mongoose uses.


Mongoose.prototype.now()

Mongoose uses this function to get the current time when setting timestamps. You may stub out this function using a tool like Sinon for testing.


Mongoose.prototype.plugin()

Parameters
  • fn «Function» plugin callback

  • [opts] «Object» optional options

Returns:
  • «Mongoose» this

Declares a global plugin executed on all Schemas.

Equivalent to calling .plugin(fn) on each Schema you create.


Mongoose.prototype.pluralize()

Parameters
  • [fn] «Function|null» overwrites the function used to pluralize collection names

Returns:
  • «Function,null» the current function used to pluralize collection names, defaults to the legacy function from mongoose-legacy-pluralize.

Getter/setter around function for pluralizing collection names.


Mongoose.prototype.set()

Parameters
  • key «String»
  • value «String|Function|Boolean»

Sets mongoose options

Example:

mongoose.set('test', value) // sets the 'test' option to `value`

mongoose.set('debug', true) // enable logging collection methods + arguments to the console/file

mongoose.set('debug', function(collectionName, methodName, ...methodArgs) {}); // use custom function to log collection methods + arguments

Currently supported options are

  • 'debug': If true, prints the operations mongoose sends to MongoDB to the console. If a writable stream is passed, it will log to that stream, without colorization. If a callback function is passed, it will receive the collection name, the method name, then all arugments passed to the method. For example, if you wanted to replicate the default logging, you could output from the callback Mongoose: ${collectionName}.${methodName}(${methodArgs.join(', ')}).
  • 'returnOriginal': If false, changes the default returnOriginal option to findOneAndUpdate(), findByIdAndUpdate, and findOneAndReplace() to false. This is equivalent to setting the new option to true for findOneAndX() calls by default. Read our findOneAndUpdate() tutorial for more information.
  • 'bufferCommands': enable/disable mongoose's buffering mechanism for all connections and models
  • 'useCreateIndex': false by default. Set to true to make Mongoose's default index build use createIndex() instead of ensureIndex() to avoid deprecation warnings from the MongoDB driver.
  • 'useFindAndModify': true by default. Set to false to make findOneAndUpdate() and findOneAndRemove() use native findOneAndUpdate() rather than findAndModify().
  • 'useNewUrlParser': false by default. Set to true to make all connections set the useNewUrlParser option by default
  • 'useUnifiedTopology': false by default. Set to true to make all connections set the useUnifiedTopology option by default
  • 'cloneSchemas': false by default. Set to true to clone() all schemas before compiling into a model.
  • 'applyPluginsToDiscriminators': false by default. Set to true to apply global plugins to discriminator schemas. This typically isn't necessary because plugins are applied to the base schema and discriminators copy all middleware, methods, statics, and properties from the base schema.
  • 'applyPluginsToChildSchemas': true by default. Set to false to skip applying global plugins to child schemas
  • 'objectIdGetter': true by default. Mongoose adds a getter to MongoDB ObjectId's called _id that returns this for convenience with populate. Set this to false to remove the getter.
  • 'runValidators': false by default. Set to true to enable update validators for all validators by default.
  • 'toObject': { transform: true, flattenDecimals: true } by default. Overwrites default objects to toObject()
  • 'toJSON': { transform: true, flattenDecimals: true } by default. Overwrites default objects to toJSON(), for determining how Mongoose documents get serialized by JSON.stringify()
  • 'strict': true by default, may be false, true, or 'throw'. Sets the default strict mode for schemas.
  • 'strictQuery': false by default, may be false, true, or 'throw'. Sets the default strictQuery mode for schemas.
  • 'selectPopulatedPaths': true by default. Set to false to opt out of Mongoose adding all fields that you populate() to your select(). The schema-level option selectPopulatedPaths overwrites this one.
  • 'typePojoToMixed': true by default, may be false or true. Sets the default typePojoToMixed for schemas.
  • 'maxTimeMS': If set, attaches maxTimeMS to every query
  • 'autoIndex': true by default. Set to false to disable automatic index creation for all models associated with this Mongoose instance.

Mongoose.prototype.startSession()

Parameters
  • [options] «Object» see the mongodb driver options

    • [options.causalConsistency=true] «Boolean» set to false to disable causal consistency

  • [callback] «Function»
Returns:
  • «Promise<ClientSession>» promise that resolves to a MongoDB driver ClientSession

Requires MongoDB >= 3.6.0. Starts a MongoDB session for benefits like causal consistency, retryable writes, and transactions.

Calling mongoose.startSession() is equivalent to calling mongoose.connection.startSession(). Sessions are scoped to a connection, so calling mongoose.startSession() starts a session on the default mongoose connection.


Mongoose.prototype.version

Type:
  • «property»

The Mongoose version

Example

console.log(mongoose.version); // '5.x.x'