Method: ActiveRecord::Serialization#to_json

Defined in:
lib/active_record/serializers/json_serializer.rb

#to_json(options = {}) ⇒ Object

Returns a JSON string representing the model. Some configuration is available through options.

The option ActiveRecord::Base.include_root_in_json controls the top-level behavior of to_json. In a new Rails application, it is set to true in initializers/new_rails_defaults.rb. When it is true, to_json will emit a single root node named after the object's type. For example:

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

ActiveRecord::Base.include_root_in_json = false
konata.to_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 set to false.

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

konata = User.find(1)
konata.to_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:

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

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

To include any methods on the model, use :methods.

konata.to_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.

konata.to_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"}]}

2nd level and higher order associations work as well:

konata.to_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"}]}


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# File 'lib/active_record/serializers/json_serializer.rb', line 76

def to_json(options = {})
  super
end