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

Expose connection states for user-land

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 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@127.0.0.1:port/database');

// replica sets
const uri = 'mongodb://user:pass@127.0.0.1:port,anotherhost:port,yetanother:port/mydatabase';
mongoose.connect(uri);

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

// Using `await` throws "MongooseServerSelectionError: Server selection timed out after 30000 ms"
// if Mongoose can't connect.
const uri = 'mongodb://nonexistent.domain:27000';
await mongoose.connect(uri);

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://127.0.0.1:27017/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@127.0.0.1:port/database');

// and options
const opts = { db: { native_parser: true }}
db = mongoose.createConnection('mongodb://user:pass@127.0.0.1:port/database', opts);

// replica sets
db = mongoose.createConnection('mongodb://user:pass@127.0.0.1:port,anotherhost:port,yetanother:port/database');

// and options
const opts = { replset: { strategy: 'ping', rs_name: 'testSet' }}
db = mongoose.createConnection('mongodb://user:pass@127.0.0.1:port,anotherhost:port,yetanother:port/database', opts);

// initialize now, connect later
db = mongoose.createConnection();
await db.openUri('mongodb://127.0.0.1:27017/database');

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 the given value is a Mongoose ObjectId (using instanceof) or if the given value is a 24 character hex string, which is the most commonly used string representation of an ObjectId.

This function is similar to isValidObjectId(), but considerably more strict, because isValidObjectId() will return true for any value that Mongoose can convert to an ObjectId. That includes Mongoose documents, any string of length 12, and any number. isObjectIdOrHexString() returns true only for ObjectId instances or 24 character hex strings, and will return false for numbers, documents, and strings of length 12.

Example:

mongoose.isObjectIdOrHexString(new mongoose.Types.ObjectId()); // true
mongoose.isObjectIdOrHexString('62261a65d66c6be0a63c051f'); // true

mongoose.isObjectIdOrHexString('0123456789ab'); // false
mongoose.isObjectIdOrHexString(6); // false
mongoose.isObjectIdOrHexString(new User({ name: 'test' })); // false
mongoose.isObjectIdOrHexString({ test: 42 }); // false

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); // true
mongoose.isValidObjectId(new User({ name: 'test' })); // true

mongoose.isValidObjectId({ test: 42 }); // 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 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.

Takes in an object and deletes any keys from the object whose values are strictly equal to undefined. This function is useful for query filters because Mongoose treats TestModel.find({ name: undefined }) as TestModel.find({ name: null }).

Example:

const filter = { name: 'John', age: undefined, status: 'active' };
mongoose.omitUndefined(filter); // { name: 'John', status: 'active' }
filter; // { name: 'John', status: 'active' }

await UserModel.findOne(mongoose.omitUndefined(filter));

Use this function in post() middleware to replace the result

Example:

schema.post('find', function(res) {
  // Normally you have to modify `res` in place. But with
  // `overwriteMiddlewarResult()`, you can make `find()` return a
  // completely different value.
  return mongoose.overwriteMiddlewareResult(res.filter(doc => !doc.isDeleted));
});

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.

Sanitizes query filters against query selector injection attacks by wrapping any nested objects that have a property whose name starts with $ in a $eq.

const obj = { username: 'val', pwd: { $ne: null } };
sanitizeFilter(obj);
obj; // { username: 'val', pwd: { $eq: { $ne: null } } });

Sets mongoose options

key can be used a object to set multiple options at once. If a error gets thrown for one option, other options will still be evaluated.

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

mongoose.set({ debug: true, autoIndex: false }); // set multiple options at once

Currently supported options are:

• allowDiskUse: Set to true to set allowDiskUse to true to all aggregation operations by default.
• applyPluginsToChildSchemas: true by default. Set to false to skip applying global plugins to child schemas
• 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.
• 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.
• autoIndex: true by default. Set to false to disable automatic index creation for all models associated with this Mongoose instance.
• bufferCommands: enable/disable mongoose's buffering mechanism for all connections and models
• bufferTimeoutMS: If bufferCommands is on, this option sets the maximum amount of time Mongoose buffering will wait before throwing an error. If not specified, Mongoose will use 10000 (10 seconds).
• cloneSchemas: false by default. Set to true to clone() all schemas before compiling into a model.
• 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 arguments 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(', ')}).
• id: If true, adds a id virtual to all schemas unless overwritten on a per-schema basis.
• timestamps.createdAt.immutable: true by default. If false, it will change the createdAt field to be immutable: false which means you can update the createdAt
• maxTimeMS: If set, attaches maxTimeMS to every query
• 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.
• overwriteModels: Set to true to default to overwriting models with the same name when calling mongoose.model(), as opposed to throwing an OverwriteModelError.
• 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.
• runValidators: false by default. Set to true to enable update validators for all validators by default.
• sanitizeFilter: false by default. Set to true to enable the sanitization of the query filters against query selector injection attacks by wrapping any nested objects that have a property whose name starts with $ in a $eq.
• 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.
• 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.
• toJSON: { transform: true, flattenDecimals: true } by default. Overwrites default objects to toJSON(), for determining how Mongoose documents get serialized by JSON.stringify()
• toObject: { transform: true, flattenDecimals: true } by default. Overwrites default objects to toObject()

Overwrites the current driver used by this Mongoose instance. A driver is a Mongoose-specific interface that defines functions like find().

Use this function in pre() middleware to skip calling the wrapped function.

Example:

schema.pre('save', function() {
  // Will skip executing `save()`, but will execute post hooks as if
  // `save()` had executed with the result `{ matchedCount: 0 }`
  return mongoose.skipMiddlewareFunction({ matchedCount: 0 });
});

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.

Syncs all the indexes for the models registered with this connection.

Tells sanitizeFilter() to skip the given object when filtering out potential query selector injection attacks. Use this method when you have a known query selector that you want to use.

const obj = { username: 'val', pwd: trusted({ $type: 'string', $eq: 'my secret' }) };
sanitizeFilter(obj);

// Note that `sanitizeFilter()` did not add `$eq` around `$type`.
obj; // { username: 'val', pwd: { $type: 'string', $eq: 'my secret' } });

The Mongoose version

Example:

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