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Embedded Documents

Embedded documents are documents with schemas of their own that are part of other documents (as items within an array).

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.

Definition and initialization

When you define a Schema like this:

var Comments = new Schema({
    title     : String
  , body      : String
  , date      : Date

var BlogPost = new Schema({
    author    : ObjectId
  , title     : String
  , body      : String
  , date      : Date
  , comments  : [Comments]
  , meta      : {
        votes : Number
      , favs  : Number

mongoose.model('BlogPost', BlogPost);

The comments key of your BlogPost documents will then be an instance of DocumentArray. This is a special subclassed Array that can deal with casting, and has special methods to work with embedded documents.

Adding an embedded document to an array

// 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' }); (err) {
  if (!err) console.log('Success!');

Removing an embedded document

BlogPost.findById(myId, function (err, post) {
  if (!err) {
    post.comments[0].remove(); (err) {
      // do something

Finding an embedded document by id

DocumentArrays have an special method id that filters your embedded documents by their _id property (each embedded document gets one):

Consider the following snippet:; (err) {
  // embedded comment with id `my_id` removed!