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Module: ActiveModel::Serializers::JSON

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Included In:
::ActiveRecord::Base, ::ActiveRecord::Serialization
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::ActiveSupport::Concern
Instance Chain:
self, ::ActiveModel::Serialization
Defined in: activemodel/lib/active_model/serializers/json.rb

Overview

Active Model JSON Serializer

Class Method Summary

::ActiveSupport::Concern - Extended

class_methods

Define class methods from given block.
included

Evaluate given block in context of base class, so that you can write class macros here.
prepended

Evaluate given block in context of base class, so that you can write class macros here.

Instance Method Summary

::ActiveModel::Serialization - Included

#read_attribute_for_serialization

Hook method defining how an attribute value should be retrieved for serialization.
#serializable_hash

Returns a serialized hash of your object.

DSL Calls

included

[ GitHub ] 


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# File 'activemodel/lib/active_model/serializers/json.rb', line 12

included do
  extend ActiveModel::Naming

  class_attribute :include_root_in_json, instance_writer: false, default: false
end

Instance Method Details

#as_json(options = nil)

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" } ] }
[ GitHub ] 

  


# 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


  








  

    #from_json(json, include_root = include_root_in_json)  
  



  

    

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


  



  [ GitHub ]


  

  


# 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