SchemaTypes handle definition of path defaults, validation, getters, setters, field selection defaults for queries, and other general characteristics for Strings and Numbers.

The following are all the valid SchemaTypes in mongoose.


var schema = new Schema({
  name:    String,
  binary:  Buffer,
  living:  Boolean,
  updated: { type: Date, default: },
  age:     { type: Number, min: 18, max: 65 },
  mixed:   Schema.Types.Mixed,
  _someId: Schema.Types.ObjectId,
  decimal: Schema.Types.Decimal128,
  array: [],
  ofString: [String],
  ofNumber: [Number],
  ofDates: [Date],
  ofBuffer: [Buffer],
  ofBoolean: [Boolean],
  ofMixed: [Schema.Types.Mixed],
  ofObjectId: [Schema.Types.ObjectId],
  ofArrays: [[]],
  ofArrayOfNumbers: [[Number]],
  nested: {
    stuff: { type: String, lowercase: true, trim: true }
  map: Map,
  mapOfString: {
    type: Map,
    of: String

// example use

var Thing = mongoose.model('Thing', schema);

var m = new Thing; = 'Statue of Liberty';
m.age = 125;
m.updated = new Date;
m.binary = new Buffer(0); = false;
m.mixed = { any: { thing: 'i want' } };
m._someId = new mongoose.Types.ObjectId;
m.ofDates.addToSet(new Date);
m.ofMixed = [1, [], 'three', { four: 5 }];
m.nested.stuff = 'good'; = new Map([['key', 'value']]);;

SchemaType Options

You can declare a schema type using the type directly, or an object with a type property.

var schema1 = new Schema({
  test: String // `test` is a path of type String

var schema2 = new Schema({
  test: { type: String } // `test` is a path of type string

In addition to the type property, you can specify additional properties for a path. For example, if you want to lowercase a string before saving:

var schema2 = new Schema({
  test: {
    type: String,
    lowercase: true // Always convert `test` to lowercase

The lowercase property only works for strings. There are certain options which apply for all schema types, and some that apply for specific schema types.

All Schema Types
  • required: boolean or function, if true adds a required validator for this property
  • default: Any or function, sets a default value for the path. If the value is a function, the return value of the function is used as the default.
  • select: boolean, specifies default projections for queries
  • validate: function, adds a validator function for this property
  • get: function, defines a custom getter for this property using Object.defineProperty().
  • set: function, defines a custom setter for this property using Object.defineProperty().
  • alias: string, mongoose >= 4.10.0 only. Defines a virtual with the given name that gets/sets this path.
var numberSchema = new Schema({
  integerOnly: {
    type: Number,
    get: v => Math.round(v),
    set: v => Math.round(v),
    alias: 'i'

var Number = mongoose.model('Number', numberSchema);

var doc = new Number();
doc.integerOnly = 2.001;
doc.integerOnly; // 2
doc.i; // 2
doc.i = 3.001;
doc.integerOnly; // 3
doc.i; // 3

You can also define MongoDB indexes using schema type options.

  • index: boolean, whether to define an index on this property.
  • unique: boolean, whether to define a unique index on this property.
  • sparse: boolean, whether to define a sparse index on this property.
var schema2 = new Schema({
  test: {
    type: String,
    index: true,
    unique: true // Unique index. If you specify `unique: true`
    // specifying `index: true` is optional if you do `unique: true`
  • lowercase: boolean, whether to always call .toLowerCase() on the value
  • uppercase: boolean, whether to always call .toUpperCase() on the value
  • trim: boolean, whether to always call .trim() on the value
  • match: RegExp, creates a validator that checks if the value matches the given regular expression
  • enum: Array, creates a validator that checks if the value is in the given array.
  • minlength: Number, creates a validator that checks if the value length is not less then the given number
  • maxlength: Number, creates a validator that checks if the value length is not greater then the given number
  • min: Number, creates a validator that checks if the value is greater than or equal to the given minimum.
  • max: Number, creates a validator that checks if the value is less than or equal to the given maximum.
  • min: Date
  • max: Date

Usage notes


Built-in Date methods are not hooked into the mongoose change tracking logic which in English means that if you use a Date in your document and modify it with a method like setMonth(), mongoose will be unaware of this change and will not persist this modification. If you must modify Date types using built-in methods, tell mongoose about the change with doc.markModified('pathToYourDate') before saving.

var Assignment = mongoose.model('Assignment', { dueDate: Date });
Assignment.findOne(function (err, doc) {
  doc.dueDate.setMonth(3);; // THIS DOES NOT SAVE YOUR CHANGE

  doc.markModified('dueDate');; // works


An "anything goes" SchemaType, its flexibility comes at a trade-off of it being harder to maintain. Mixed is available either through Schema.Types.Mixed or by passing an empty object literal. The following are equivalent:

var Any = new Schema({ any: {} });
var Any = new Schema({ any: Object });
var Any = new Schema({ any: Schema.Types.Mixed });

Since it is a schema-less type, you can change the value to anything else you like, but Mongoose loses the ability to auto detect and save those changes. To "tell" Mongoose that the value of a Mixed type has changed, call the .markModified(path) method of the document passing the path to the Mixed type you just changed.

person.anything = { x: [3, 4, { y: "changed" }] };
person.markModified('anything');; // anything will now get saved


To specify a type of ObjectId, use Schema.Types.ObjectId in your declaration.

var mongoose = require('mongoose');
var ObjectId = mongoose.Schema.Types.ObjectId;
var Car = new Schema({ driver: ObjectId });
// or just Schema.ObjectId for backwards compatibility with v2


Mongoose supports arrays of SchemaTypes and arrays of subdocuments. Arrays of SchemaTypes are also called primitive arrays, and arrays of subdocuments are also called document arrays.

var ToySchema = new Schema({ name: String });
var ToyBox = new Schema({
  toys: [ToySchema],
  buffers: [Buffer],
  string:  [String],
  numbers: [Number]
  // ... etc

Arrays are special because they implicitly have a default value of [] (empty array).

var Toy = mongoose.model('Test', ToySchema);
console.log((new Toy()).toys); // []

To overwrite this default, you need to set the default value to undefined

var ToySchema = new Schema({
  toys: {
    type: [ToySchema],
    default: undefined

Note: specifying an empty array is equivalent to Mixed. The following all create arrays of Mixed:

var Empty1 = new Schema({ any: [] });
var Empty2 = new Schema({ any: Array });
var Empty3 = new Schema({ any: [Schema.Types.Mixed] });
var Empty4 = new Schema({ any: [{}] });


New in Mongoose 5.1.0

A MongooseMap is a subclass of the built-in Map class. In these docs, we'll use the terms 'map' and MongooseMap interchangeably. In Mongoose, maps are how you create a nested document with arbitrary keys.

const userSchema = new Schema({
  // `socialMediaHandles` is a map whose values are strings. A map's
  // keys are always strings. You specify the type of values using `of`.
  socialMediaHandles: {
    type: Map,
    of: String

const User = mongoose.model('User', userSchema);
// Map { 'github' => 'vkarpov15', 'twitter' => '@code_barbarian' }
console.log(new User({
  socialMediaHandles: {
    github: 'vkarpov15',
    twitter: '@code_barbarian'

The above example doesn't explicitly declare github or twitter as paths, but, since socialMediaHandles is a map, you can store arbitrary key/value pairs. However, since socialMediaHandles is a map, you must use .get() to get the value of a key and .set() to set the value of a key.

const user = new User({
  socialMediaHandles: {}

// Good
user.socialMediaHandles.set('github', 'vkarpov15');
// Works too
user.set('socialMediaHandles.twitter', '@code_barbarian');
// Bad, the `myspace` property will **not** get saved
user.socialMediaHandles.myspace = 'fail';

// 'vkarpov15'
// '@code_barbarian'
// undefined

// Will only save the 'github' and 'twitter' properties;

Map types are stored as BSON objects in MongoDB. Keys in a BSON object are ordered, so this means the insertion order property of maps is maintained.

Creating Custom Types

Mongoose can also be extended with custom SchemaTypes. Search the plugins site for compatible types like mongoose-long, mongoose-int32, and other types.

The schema.path() Function

The schema.path() function returns the instantiated schema type for a given path.

var sampleSchema = new Schema({ name: { type: String, required: true } });
// Output looks like:
 * SchemaString {
 *   enumValues: [],
 *   regExp: null,
 *   path: 'name',
 *   instance: 'String',
 *   validators: ...

You can use this function to inspect the schema type for a given path, including what validators it has and what the type is.

Next Up

Now that we've covered SchemaTypes, let's take a look at Connections.

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