mongoose
    TypeScript icon, indicating that this package has built-in type declarations

    3.5.4 • Public • Published

    What's Mongoose?

    Mongoose is a MongoDB object modeling tool designed to work in an asynchronous environment.

    Defining a model is as easy as:

    var Comment = new Schema({
        title     : String
      , body      : String
      , date      : Date
    });
    
    var BlogPost = new Schema({
        author    : ObjectId
      , title     : String
      , body      : String
      , buf       : Buffer
      , date      : Date
      , comments  : [Comment]
      , meta      : {
          votes : Number
        , favs  : Number
      }
    });
    
    var Post = mongoose.model('BlogPost', BlogPost);
    

    Documentation

    mongoosejs.com

    Try it live

    Installation

    The recommended way is through the excellent NPM:

    $ npm install mongoose
    

    Otherwise, you can check it in your repository and then expose it:

    $ git clone git://github.com/LearnBoost/mongoose.git node_modules/mongoose/
    

    And install dependency modules written on package.json.

    Then you can require it:

    require('mongoose')
    

    Connecting to MongoDB

    First, we need to define a connection. If your app uses only one database, you should use mongose.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.

    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.

    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.

    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:

    The following example shows some of these features:

    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

    var myModel = mongoose.model('ModelName');
    

    Or just do it all at once

    var MyModel = mongoose.model('ModelName', mySchema);
    

    We can then instantiate it, and save it:

    var instance = new MyModel();
    instance.my.key = 'hello';
    instance.save(function (err) {
      //
    });
    

    Or we can find documents from the same collection

    MyModel.find({}, function (err, docs) {
      // docs.forEach
    });
    

    You can also findOne, findById, update, etc. For more details check out this link.

    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:

    var conn = mongoose.createConnection('your connection string');
    var MyModel = conn.model('ModelName', schema);
    var m = new MyModel;
    m.save() // works
    
    vs
    
    var conn = mongoose.createConnection('your connection string');
    var MyModel = mongoose.model('ModelName', schema);
    var 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: [Comments]
    

    Where Comments is a Schema we created. This means that creating embedded documents is as simple as:

    // 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:

    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!

    Mongoose interacts with your embedded documents in arrays atomically, out of the box.

    Middleware

    Middleware is one of the most exciting features about Mongoose. Middleware takes away all the pain of nested callbacks.

    Middleware are defined at the Schema level and are applied for the methods init (when a document is initialized with data from MongoDB), save (when a document or embedded document is saved).

    There's two types of middleware:

    • Serial Serial middleware are defined like:

        .pre(method, function (next, methodArg1, methodArg2, ...) {
          // ...
        })
      

      They're executed one after the other, when each middleware calls next.

      You can also intercept the method's incoming arguments via your middleware -- notice methodArg1, methodArg2, etc in the pre definition above. See section "Intercepting and mutating method arguments" below.

    • Parallel Parallel middleware offer more fine-grained flow control, and are defined like:

        .pre(method, true, function (next, done, methodArg1, methodArg2) {
          // ...
        })
      

      Parallel middleware can next() immediately, but the final argument will be called when all the parallel middleware have called done().

    Error handling

    If any middleware calls next or done with an Error instance, the flow is interrupted, and the error is passed to the function passed as an argument.

    For example:

    schema.pre('save', function (next) {
      // something goes wrong
      next(new Error('something went wrong'));
    });
    
    // later...
    
    myModel.save(function (err) {
      // err can come from a middleware
    });
    

    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 sets a path in your Document to a new value:

    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:

    .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:

    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
        }
    });
    

    API docs

    You can find the Dox generated API docs here.

    Getting support

    Driver access

    The driver being used defaults to node-mongodb-native and is directly accessible through YourModel.collection. Note: using the driver directly bypasses all Mongoose power-tools like validation, getters, setters, hooks, etc.

    Mongoose Plugins

    Take a peek at the plugins search site to see related modules from the community.

    Contributing to Mongoose

    Cloning the repository

    git clone git://github.com/LearnBoost/mongoose.git
    

    Guidelines

    See contributing.

    Credits

    contributors

    License

    Copyright (c) 2010-2012 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.

    Install

    npm i mongoose@3.5.4

    Version

    3.5.4

    License

    MIT

    Last publish

    Collaborators

    • aaron
    • rauchg
    • tjholowaychuk
    • vkarpov15