as_json

Returns a JSON string representing the model. Some configuration can be passed through options.

The option include_root_in_json controls the top-level behavior of as_json. If true (the default) as_json will emit a single root node named after the object’s type. For example:

user = User.find(1)
user.as_json
# => { "user": {"id": 1, "name": "Konata Izumi", "age": 16,
                "created_at": "2006/08/01", "awesome": true} }

ActiveRecord::Base.include_root_in_json = false
user.as_json
# => {"id": 1, "name": "Konata Izumi", "age": 16,
      "created_at": "2006/08/01", "awesome": true}

The remainder of the examples in this section assume include_root_in_json is false.

Without any options, the returned JSON string will include all the model’s attributes. For example:

user = User.find(1)
user.as_json
# => {"id": 1, "name": "Konata Izumi", "age": 16,
      "created_at": "2006/08/01", "awesome": true}

The :only and :except options can be used to limit the attributes included, and work similar to the attributes method. For example:

user.as_json(:only => [ :id, :name ])
# => {"id": 1, "name": "Konata Izumi"}

user.as_json(:except => [ :id, :created_at, :age ])
# => {"name": "Konata Izumi", "awesome": true}

To include the result of some method calls on the model use :methods:

user.as_json(:methods => :permalink)
# => {"id": 1, "name": "Konata Izumi", "age": 16,
      "created_at": "2006/08/01", "awesome": true,
      "permalink": "1-konata-izumi"}

To include associations use :include:

user.as_json(:include => :posts)
# => {"id": 1, "name": "Konata Izumi", "age": 16,
      "created_at": "2006/08/01", "awesome": true,
      "posts": [{"id": 1, "author_id": 1, "title": "Welcome to the weblog"},
                {"id": 2, author_id: 1, "title": "So I was thinking"}]}

Second level and higher order associations work as well:

user.as_json(:include => { :posts => {
                               :include => { :comments => {
                                             :only => :body } },
                               :only => :title } })
# => {"id": 1, "name": "Konata Izumi", "age": 16,
      "created_at": "2006/08/01", "awesome": true,
      "posts": [{"comments": [{"body": "1st post!"}, {"body": "Second!"}],
                 "title": "Welcome to the weblog"},
                {"comments": [{"body": "Don't think too hard"}],
                 "title": "So I was thinking"}]}