Mongoose

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();

The Mongoose Aggregate constructor

The Mongoose CastError constructor

The Mongoose Collection constructor

The Mongoose Connection constructor

The Mongoose Date SchemaType.

Example:

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

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 });

The Mongoose Document constructor.

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

The MongooseError constructor.

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 });

The Mongoose Model constructor.

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();

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' });

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 });

The Mongoose Promise constructor.

Storage layer for mongoose promises

The Mongoose Query constructor.

Expose connection states for user-land

The Mongoose Schema constructor

Example:

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

The Mongoose SchemaType constructor

The constructor used for schematype options

The various Mongoose SchemaTypes.

Note:

Alias of mongoose.Schema.Types for backwards compatibility.

The various Mongoose Types.

Example:

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

Types:

• Array
• Buffer
• Embedded
• DocumentArray
• Decimal128
• ObjectId
• Map
• Subdocument

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

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

The Mongoose VirtualType constructor

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.
})

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().

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

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]);

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
});

Runs .close() on all connections in parallel.

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

Gets mongoose options

Example:

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

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

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)

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

Note:

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

The node-mongodb-native driver Mongoose uses.

The mquery query builder Mongoose uses.

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.

Declares a global plugin executed on all Schemas.

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

Getter/setter around function for pluralizing collection names.

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.
• 'autoCreate': Set to true to make Mongoose call Model.createCollection() automatically when you create a model with mongoose.model() or conn.model(). This is useful for testing transactions, change streams, and other features that require the collection to exist.
• 'overwriteModels': Set to true to default to overwriting models with the same name when calling mongoose.model(), as opposed to throwing an OverwriteModelError.

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.

The Mongoose version

Example

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