# Mongoose Mongoose is a [MongoDB](https://www.mongodb.org/) object modeling tool designed to work in an asynchronous environment. [![Build Status](https://api.travis-ci.org/Automattic/mongoose.svg?branch=master)](https://travis-ci.org/Automattic/mongoose) [![Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/Automattic/mongoose?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [![NPM version](https://badge.fury.io/js/mongoose.svg)](http://badge.fury.io/js/mongoose) [![Dependency Status](https://gemnasium.com/Automattic/mongoose.svg)](https://gemnasium.com/Automattic/mongoose) ## Documentation [mongoosejs.com](http://mongoosejs.com/) ## Support - [Stack Overflow](http://stackoverflow.com/questions/tagged/mongoose) - [bug reports](https://github.com/Automattic/mongoose/issues/) - [help forum](http://groups.google.com/group/mongoose-orm) - [MongoDB support](https://docs.mongodb.org/manual/support/) - [Mongoose Slack Channel](https://mongoosejs.slack.com/) ## Plugins Check out the [plugins search site](http://plugins.mongoosejs.io/) to see hundreds of related modules from the community. Build your own Mongoose plugin through [generator-mongoose-plugin](https://github.com/huei90/generator-mongoose-plugin). ## Contributors View all 100+ [contributors](https://github.com/Automattic/mongoose/graphs/contributors). Stand up and be counted as a [contributor](https://github.com/Automattic/mongoose/blob/master/CONTRIBUTING.md) too! ## Live Examples ## Installation First install [node.js](http://nodejs.org/) and [mongodb](https://www.mongodb.org/downloads). Then: ```sh $ npm install mongoose ``` ## Stability The current stable branch is [master](https://github.com/Automattic/mongoose/tree/master). The [3.8.x](https://github.com/Automattic/mongoose/tree/3.8.x) branch contains legacy support for the 3.x release series, which is no longer under active development as of September 2015. The [3.8.x docs](http://mongoosejs.com/docs/3.8.x/) are still available. ## Overview ### Connecting to MongoDB First, we need to define a connection. If your app uses only one database, you should use `mongoose.connect`. If you need to create additional connections, use `mongoose.createConnection`. Both `connect` and `createConnection` take a `mongodb://` URI, or the parameters `host, database, port, options`. ```js var mongoose = require('mongoose'); mongoose.connect('mongodb://localhost/my_database'); ``` Once connected, the `open` event is fired on the `Connection` instance. If you're using `mongoose.connect`, the `Connection` is `mongoose.connection`. Otherwise, `mongoose.createConnection` return value is a `Connection`. **Note:** _If the local connection fails then try using 127.0.0.1 instead of localhost. Sometimes issues may arise when the local hostname has been changed._ **Important!** Mongoose buffers all the commands until it's connected to the database. This means that you don't have to wait until it connects to MongoDB in order to define models, run queries, etc. ### Defining a Model Models are defined through the `Schema` interface. ```js var Schema = mongoose.Schema, ObjectId = Schema.ObjectId; var BlogPost = new Schema({ author : ObjectId, title : String, body : String, date : Date }); ``` Aside from defining the structure of your documents and the types of data you're storing, a Schema handles the definition of: * [Validators](http://mongoosejs.com/docs/validation.html) (async and sync) * [Defaults](http://mongoosejs.com/docs/api.html#schematype_SchemaType-default) * [Getters](http://mongoosejs.com/docs/api.html#schematype_SchemaType-get) * [Setters](http://mongoosejs.com/docs/api.html#schematype_SchemaType-set) * [Indexes](http://mongoosejs.com/docs/guide.html#indexes) * [Middleware](http://mongoosejs.com/docs/middleware.html) * [Methods](http://mongoosejs.com/docs/guide.html#methods) definition * [Statics](http://mongoosejs.com/docs/guide.html#statics) definition * [Plugins](http://mongoosejs.com/docs/plugins.html) * [pseudo-JOINs](http://mongoosejs.com/docs/populate.html) The following example shows some of these features: ```js var Comment = new Schema({ name: { type: String, default: 'hahaha' }, age: { type: Number, min: 18, index: true }, bio: { type: String, match: /[a-z]/ }, date: { type: Date, default: Date.now }, buff: Buffer }); // a setter Comment.path('name').set(function (v) { return capitalize(v); }); // middleware Comment.pre('save', function (next) { notify(this.get('email')); next(); }); ``` Take a look at the example in `examples/schema.js` for an end-to-end example of a typical setup. ### Accessing a Model Once we define a model through `mongoose.model('ModelName', mySchema)`, we can access it through the same function ```js var myModel = mongoose.model('ModelName'); ``` Or just do it all at once ```js var MyModel = mongoose.model('ModelName', mySchema); ``` The first argument is the _singular_ name of the collection your model is for. **Mongoose automatically looks for the _plural_ version of your model name.** For example, if you use ```js var MyModel = mongoose.model('Ticket', mySchema); ``` Then Mongoose will create the model for your __tickets__ collection, not your __ticket__ collection. Once we have our model, we can then instantiate it, and save it: ```js var instance = new MyModel(); instance.my.key = 'hello'; instance.save(function (err) { // }); ``` Or we can find documents from the same collection ```js MyModel.find({}, function (err, docs) { // docs.forEach }); ``` You can also `findOne`, `findById`, `update`, etc. For more details check out [the docs](http://mongoosejs.com/docs/queries.html). **Important!** If you opened a separate connection using `mongoose.createConnection()` but attempt to access the model through `mongoose.model('ModelName')` it will not work as expected since it is not hooked up to an active db connection. In this case access your model through the connection you created: ```js var conn = mongoose.createConnection('your connection string'), MyModel = conn.model('ModelName', schema), m = new MyModel; m.save(); // works ``` vs ```js var conn = mongoose.createConnection('your connection string'), MyModel = mongoose.model('ModelName', schema), m = new MyModel; m.save(); // does not work b/c the default connection object was never connected ``` ### Embedded Documents In the first example snippet, we defined a key in the Schema that looks like: ``` comments: [Comment] ``` Where `Comment` is a `Schema` we created. This means that creating embedded documents is as simple as: ```js // retrieve my model var BlogPost = mongoose.model('BlogPost'); // create a blog post var post = new BlogPost(); // create a comment post.comments.push({ title: 'My comment' }); post.save(function (err) { if (!err) console.log('Success!'); }); ``` The same goes for removing them: ```js BlogPost.findById(myId, function (err, post) { if (!err) { post.comments[0].remove(); post.save(function (err) { // do something }); } }); ``` Embedded documents enjoy all the same features as your models. Defaults, validators, middleware. Whenever an error occurs, it's bubbled to the `save()` error callback, so error handling is a snap! ### Middleware See the [docs](http://mongoosejs.com/docs/middleware.html) page. #### Intercepting and mutating method arguments You can intercept method arguments via middleware. For example, this would allow you to broadcast changes about your Documents every time someone `set`s a path in your Document to a new value: ```js schema.pre('set', function (next, path, val, typel) { // `this` is the current Document this.emit('set', path, val); // Pass control to the next pre next(); }); ``` Moreover, you can mutate the incoming `method` arguments so that subsequent middleware see different values for those arguments. To do so, just pass the new values to `next`: ```js .pre(method, function firstPre (next, methodArg1, methodArg2) { // Mutate methodArg1 next("altered-" + methodArg1.toString(), methodArg2); }); // pre declaration is chainable .pre(method, function secondPre (next, methodArg1, methodArg2) { console.log(methodArg1); // => 'altered-originalValOfMethodArg1' console.log(methodArg2); // => 'originalValOfMethodArg2' // Passing no arguments to `next` automatically passes along the current argument values // i.e., the following `next()` is equivalent to `next(methodArg1, methodArg2)` // and also equivalent to, with the example method arg // values, `next('altered-originalValOfMethodArg1', 'originalValOfMethodArg2')` next(); }); ``` #### Schema gotcha `type`, when used in a schema has special meaning within Mongoose. If your schema requires using `type` as a nested property you must use object notation: ```js new Schema({ broken: { type: Boolean }, asset : { name: String, type: String // uh oh, it broke. asset will be interpreted as String } }); new Schema({ works: { type: Boolean }, asset: { name: String, type: { type: String } // works. asset is an object with a type property } }); ``` ### Driver Access Mongoose is built on top of the [official MongoDB Node.js driver](https://github.com/mongodb/node-mongodb-native). Each mongoose model keeps a reference to a [native MongoDB driver collection](http://mongodb.github.io/node-mongodb-native/2.1/api/Collection.html). The collection object can be accessed using `YourModel.collection`. However, using the collection object directly bypasses all mongoose features, including hooks, validation, etc. The one notable exception that `YourModel.collection` still buffers commands. As such, `YourModel.collection.find()` will **not** return a cursor. ## API Docs Find the API docs [here](http://mongoosejs.com/docs/api.html), generated using [dox](https://github.com/tj/dox) and [acquit](https://github.com/vkarpov15/acquit). ## License Copyright (c) 2010 LearnBoost <dev@learnboost.com> Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.