Active Model JSON Serializer¶ ↑

Returns a hash 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, as_json will emit a single root node named after the object’s type. The default value for include_root_in_json option is false.

user = User.find(1) user.as_json # => { "id" => 1, "name" => "Konata Izumi", "age" => 16, # "created_at" => "2006-08-01T17:27:133.000Z", "awesome" => true} ActiveRecord::Base.include_root_in_json = true user.as_json # => { "user" => { "id" => 1, "name" => "Konata Izumi", "age" => 16, # "created_at" => "2006-08-01T17:27:13.000Z", "awesome" => true } } 

This behavior can also be achieved by setting the :root option to true as in:

user = User.find(1) user.as_json(root: true) # => { "user" => { "id" => 1, "name" => "Konata Izumi", "age" => 16, # "created_at" => "2006-08-01T17:27:13.000Z", "awesome" => true } } 

If you prefer, :root may also be set to a custom string key instead as in:

user = User.find(1) user.as_json(root: "author") # => { "author" => { "id" => 1, "name" => "Konata Izumi", "age" => 16, # "created_at" => "2006-08-01T17:27:13.000Z", "awesome" => true } } 

Without any options, the returned Hash will include all the model’s attributes.

user = User.find(1) user.as_json # => { "id" => 1, "name" => "Konata Izumi", "age" => 16, # "created_at" => "2006-08-01T17:27:13.000Z", "awesome" => true} 

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

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" => "2006-08-01T17:27:13.000Z", "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" => "2006-08-01T17:27:13.000Z", "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" => "2006-08-01T17:27:13.000Z", "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" } ] } 

# File activemodel/lib/active_model/serializers/json.rb, line 96 def as_json(options = nil) root = if options && options.key?(:root) options[:root] else include_root_in_json end hash = serializable_hash(options).as_json if root root = model_name.element if root == true { root => hash } else hash end end

Sets the model attributes from a JSON string. Returns self.

class Person include ActiveModel::Serializers::JSON attr_accessor :name, :age, :awesome def attributes=(hash) hash.each do |key, value| send("#{key}=", value) end end def attributes instance_values end end json = { name: 'bob', age: 22, awesome:true }.to_json person = Person.new person.from_json(json) # => #<Person:0x007fec5e7a0088 @age=22, @awesome=true, @name="bob"> person.name # => "bob" person.age # => 22 person.awesome # => true 

The default value for include_root is false. You can change it to true if the given JSON string includes a single root node.

json = { person: { name: 'bob', age: 22, awesome:true } }.to_json person = Person.new person.from_json(json, true) # => #<Person:0x007fec5e7a0088 @age=22, @awesome=true, @name="bob"> person.name # => "bob" person.age # => 22 person.awesome # => true 

# File activemodel/lib/active_model/serializers/json.rb, line 146 def from_json(json, include_root = include_root_in_json) hash = ActiveSupport::JSON.decode(json) hash = hash.values.first if include_root self.attributes = hash self end