Mongoose is a MongoDB object modeling tool designed to work in an asynchronous environment.
Defining a model is as easy as:
var Comments = new Schema({
title : String
, body : String
, date : Date
});
var BlogPost = new Schema({
author : ObjectId
, title : String
, body : String
, buf : Buffer
, date : Date
, comments : [Comments]
, meta : {
votes : Number
, favs : Number
}
});
var Post = mongoose.model('BlogPost', BlogPost);
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')
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.
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:
- Validators (async and sync)
- Defaults
- Getters
- Setters
- Indexes
- Middleware
- Methods definition
- Statics definition
- Plugins
- DBRefs
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.
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
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 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 -- noticemethodArg1
,methodArg2
, etc in thepre
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 calleddone()
.
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
});
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:
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();
})
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
}
});
You can find the Dox generated API docs here.
Please subscribe to the Google Groups mailing list.
Join #mongoosejs on freenode.
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.
The following plugins are currently available for use with mongoose:
- mongoose-types - Adds several additional types (e.g., Email) that you can use in your Schema declarations
- mongoose-auth - A drop in solution for your auth needs. Currently supports Password, Facebook, Twitter, Github, and more.
- mongoose-joins - Adds simple join support
- mongoose-dbref - An alternative DBRef option
- mongoose-flatmatcher - A query pre-processor that maps flat name/value pairs to schemas
- mongoose-ttl - TTL support
- mongoose-keywordize - auto keywords generation
Make a fork of mongoose
, then clone it in your computer. The v2.x
branch contains the current stable release, and the master
branch the next upcoming major release.
- Please write inline documentation for new methods or class members.
- Please write tests and make sure your tests pass.
- Before starting to write code, look for existing tickets or create one for your specific issue (unless you're addressing something that's clearly broken). That way you avoid working on something that might not be of interest or that has been addressed already in a different branch.
- Guillermo Rauch - [email protected] - Guille
- Nathan White - nw
- Brian Noguchi - bnoguchi
- Aaron Heckmann - aheckmann
Copyright (c) 2010-2012 LearnBoost <[email protected]>
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