change AMS::JSON.include_root_in_json default value to false

Changes:

* Update `include_root_in_json` default value to false for default value
  to false for `ActiveModel::Serializers::JSON`.
* Remove unnecessary change to include_root_in_json option in
  wrap_parameters template.
* Update `as_json` documentation.
* Fix JSONSerialization tests.

Problem:

It's confusing that AM serializers behave differently from AR,
even when AR objects include AM serializers module.

    class User < ActiveRecord::Base; end

    class Person
      include ActiveModel::Model
      include ActiveModel::AttributeMethods
      include ActiveModel::Serializers::JSON

      attr_accessor :name, :age

      def attributes
        instance_values
      end
    end

    user.as_json
    => {"id"=>1, "name"=>"Konata Izumi", "age"=>16, "awesome"=>true}
    # root is not included

    person.as_json
    => {"person"=>{"name"=>"Francesco", "age"=>22}}
    # root is included

    ActiveRecord::Base.include_root_in_json
    => false

    Person.include_root_in_json
    => true

    # different default values for include_root_in_json

Proposal:

Change the default value of AM serializers to false, update
the misleading documentation and remove unnecessary change
to false of include_root_in_json option with AR objects.

    class User < ActiveRecord::Base; end

    class Person
      include ActiveModel::Model
      include ActiveModel::AttributeMethods
      include ActiveModel::Serializers::JSON

      attr_accessor :name, :age

      def attributes
        instance_values
      end
    end

    user.as_json
    => {"id"=>1, "name"=>"Konata Izumi", "age"=>16, "awesome"=>true}
    # root is not included

    person.as_json
    => {"name"=>"Francesco", "age"=>22}
    # root is not included

    ActiveRecord::Base.include_root_in_json
    => false

    Person.include_root_in_json
    => false

    # same behaviour, more consistent

Fixes #6578.

activemodel/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
 
+*   Changed `AM::Serializers::JSON.include_root_in_json' default value to false.
+    Now, AM Serializers and AR objects have the same default behaviour. Fixes #6578.
+
+        class User < ActiveRecord::Base; end
+
+        class Person
+          include ActiveModel::Model
+          include ActiveModel::AttributeMethods
+          include ActiveModel::Serializers::JSON
+
+          attr_accessor :name, :age
+
+          def attributes
+            instance_values
+          end
+        end
+
+        user.as_json
+        => {"id"=>1, "name"=>"Konata Izumi", "age"=>16, "awesome"=>true}
+        # root is not included
+
+        person.as_json
+        => {"name"=>"Francesco", "age"=>22}
+        # root is not included
+
+    *Francesco Rodriguez*
+
 *   Passing false hash values to `validates` will no longer enable the corresponding validators *Steve Purcell*
 
 *   `ConfirmationValidator` error messages will attach to `:#{attribute}_confirmation` instead of `attribute` *Brian Cardarella*

activemodel/lib/active_model/serializers/json.rb

@@ -13,80 +13,80 @@ module JSON
         extend ActiveModel::Configuration
 
         config_attribute :include_root_in_json
-        self.include_root_in_json = true
+        self.include_root_in_json = false
       end
 
       # Returns a hash representing the model. Some configuration can be
       # passed through +options+.
       #
       # The option <tt>include_root_in_json</tt> 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:
+      # of +as_json+. If true +as_json+ will emit a single root node named after
+      # the object's type. The default value for <tt>include_root_in_json</tt>
+      # option is +false+.
       #
       #   user = User.find(1)
       #   user.as_json
-      #   # => { "user": {"id": 1, "name": "Konata Izumi", "age": 16,
-      #                   "created_at": "2006/08/01", "awesome": true} }
+      #   # => { "id" => 1, "name" => "Konata Izumi", "age" => 16,
+      #   #     "created_at" => "2006/08/01", "awesome" => true}
+      #
+      #   ActiveRecord::Base.include_root_in_json = 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}
+      #   # => { "user" => { "id" => 1, "name" => "Konata Izumi", "age" => 16,
+      #   #                  "created_at" => "2006/08/01", "awesome" => true } }
       #
-      # This behavior can also be achieved by setting the <tt>:root</tt> option to +false+ as in:
+      # This behavior can also be achieved by setting the <tt>:root</tt> option
+      # to +true+ as in:
       #
       #   user = User.find(1)
-      #   user.as_json(root: false)
-      #   # =>  {"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
-      # <tt>false</tt>.
+      #   user.as_json(root: true)
+      #   # => { "user" => { "id" => 1, "name" => "Konata Izumi", "age" => 16,
+      #   #                  "created_at" => "2006/08/01", "awesome" => true } }
       #
       # Without any +options+, the returned Hash will include all the model's
-      # attributes. For example:
+      # attributes.
       #
       #   user = User.find(1)
       #   user.as_json
-      #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
-      #         "created_at": "2006/08/01", "awesome": true}
+      #   # => { "id" => 1, "name" => "Konata Izumi", "age" => 16,
+      #   #      "created_at" => "2006/08/01", "awesome" => true}
       #
-      # The <tt>:only</tt> and <tt>:except</tt> options can be used to limit the attributes
-      # included, and work similar to the +attributes+ method. For example:
+      # The <tt>:only</tt> and <tt>:except</tt> 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(only: [:id, :name])
+      #   # => { "id" => 1, "name" => "Konata Izumi" }
       #
-      #   user.as_json(:except => [ :id, :created_at, :age ])
-      #   # => {"name": "Konata Izumi", "awesome": true}
+      #   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 <tt>:methods</tt>:
       #
-      #   user.as_json(:methods => :permalink)
-      #   # => {"id": 1, "name": "Konata Izumi", "age": 16,
-      #         "created_at": "2006/08/01", "awesome": true,
-      #         "permalink": "1-konata-izumi"}
+      #   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 <tt>:include</tt>:
       #
-      #   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"}]}
+      #   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"}]}
+      #   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" } ] }
       def as_json(options = nil)
         root = include_root_in_json
         root = options[:root] if options.try(:key?, :root)
@@ -106,4 +106,4 @@ def from_json(json, include_root=include_root_in_json)
       end
     end
   end
-end
+end
\ No newline at end of file

activemodel/test/cases/serializers/json_serialization_test.rb

@@ -31,10 +31,15 @@ def setup
     @contact.preferences = { 'shows' => 'anime' }
   end
 
-  test "should include root in json" do
+  def teardown
+    # set to the default value
+    Contact.include_root_in_json = false
+  end
+
+  test "should not include root in json (class method)" do
     json = @contact.to_json
 
-    assert_match %r{^\{"contact":\{}, json
+    assert_no_match %r{^\{"contact":\{}, json
     assert_match %r{"name":"Konata Izumi"}, json
     assert_match %r{"age":16}, json
     assert json.include?(%("created_at":#{ActiveSupport::JSON.encode(Time.utc(2006, 8, 1))}))
@@ -42,41 +47,31 @@ def setup
     assert_match %r{"preferences":\{"shows":"anime"\}}, json
   end
 
-  test "should not include root in json (class method)" do
-    begin
-      Contact.include_root_in_json = false
-      json = @contact.to_json
-
-      assert_no_match %r{^\{"contact":\{}, json
-      assert_match %r{"name":"Konata Izumi"}, json
-      assert_match %r{"age":16}, json
-      assert json.include?(%("created_at":#{ActiveSupport::JSON.encode(Time.utc(2006, 8, 1))}))
-      assert_match %r{"awesome":true}, json
-      assert_match %r{"preferences":\{"shows":"anime"\}}, json
-    ensure
-      Contact.include_root_in_json = true
-    end
+  test "should include root in json if include_root_in_json is true" do
+    Contact.include_root_in_json = true
+    json = @contact.to_json
+
+    assert_match %r{^\{"contact":\{}, json
+    assert_match %r{"name":"Konata Izumi"}, json
+    assert_match %r{"age":16}, json
+    assert json.include?(%("created_at":#{ActiveSupport::JSON.encode(Time.utc(2006, 8, 1))}))
+    assert_match %r{"awesome":true}, json
+    assert_match %r{"preferences":\{"shows":"anime"\}}, json
   end
 
   test "should include root in json (option) even if the default is set to false" do
-    begin
-      Contact.include_root_in_json = false
-      json = @contact.to_json(:root => true)
-      assert_match %r{^\{"contact":\{}, json
-    ensure
-      Contact.include_root_in_json = true
-    end
+    json = @contact.to_json(root: true)
+    assert_match %r{^\{"contact":\{}, json
   end
 
   test "should not include root in json (option)" do
-
-    json = @contact.to_json(:root => false)
+    json = @contact.to_json(root: false)
 
     assert_no_match %r{^\{"contact":\{}, json
   end
 
   test "should include custom root in json" do
-    json = @contact.to_json(:root => 'json_contact')
+    json = @contact.to_json(root: 'json_contact')
 
     assert_match %r{^\{"json_contact":\{}, json
     assert_match %r{"name":"Konata Izumi"}, json
@@ -107,7 +102,7 @@ def setup
   end
 
   test "should allow attribute filtering with except" do
-    json = @contact.to_json(:except => [:name, :age])
+    json = @contact.to_json(except: [:name, :age])
 
     assert_no_match %r{"name":"Konata Izumi"}, json
     assert_no_match %r{"age":16}, json
@@ -122,10 +117,10 @@ def @contact.label; "Has cheezburger"; end
     def @contact.favorite_quote; "Constraints are liberating"; end
 
     # Single method.
-    assert_match %r{"label":"Has cheezburger"}, @contact.to_json(:only => :name, :methods => :label)
+    assert_match %r{"label":"Has cheezburger"}, @contact.to_json(only: :name, methods: :label)
 
     # Both methods.
-    methods_json = @contact.to_json(:only => :name, :methods => [:label, :favorite_quote])
+    methods_json = @contact.to_json(only: :name, methods: [:label, :favorite_quote])
     assert_match %r{"label":"Has cheezburger"}, methods_json
     assert_match %r{"favorite_quote":"Constraints are liberating"}, methods_json
   end
@@ -143,14 +138,15 @@ def @contact.favorite_quote; "Constraints are liberating"; end
   end
 
   test "serializable_hash should not modify options passed in argument" do
-    options = { :except => :name }
+    options = { except: :name }
     @contact.serializable_hash(options)
 
     assert_nil options[:only]
     assert_equal :name, options[:except]
   end
 
-  test "as_json should return a hash" do
+  test "as_json should return a hash if include_root_in_json is true" do
+    Contact.include_root_in_json = true
     json = @contact.as_json
 
     assert_kind_of Hash, json
@@ -160,7 +156,7 @@ def @contact.favorite_quote; "Constraints are liberating"; end
     end
   end
 
-  test "from_json should set the object's attributes" do
+  test "from_json should work without a root (class attribute)" do
     json = @contact.to_json
     result = Contact.new.from_json(json)
 
@@ -172,7 +168,7 @@ def @contact.favorite_quote; "Constraints are liberating"; end
   end
 
   test "from_json should work without a root (method parameter)" do
-    json = @contact.to_json(:root => false)
+    json = @contact.to_json
     result = Contact.new.from_json(json, false)
 
     assert_equal result.name, @contact.name
@@ -182,24 +178,19 @@ def @contact.favorite_quote; "Constraints are liberating"; end
     assert_equal result.preferences, @contact.preferences
   end
 
-  test "from_json should work without a root (class attribute)" do
-    begin
-      Contact.include_root_in_json = false
-      json = @contact.to_json
-      result = Contact.new.from_json(json)
-
-      assert_equal result.name, @contact.name
-      assert_equal result.age, @contact.age
-      assert_equal Time.parse(result.created_at), @contact.created_at
-      assert_equal result.awesome, @contact.awesome
-      assert_equal result.preferences, @contact.preferences
-    ensure
-      Contact.include_root_in_json = true
-    end
+  test "from_json should work with a root (method parameter)" do
+    json = @contact.to_json(root: :true)
+    result = Contact.new.from_json(json, true)
+
+    assert_equal result.name, @contact.name
+    assert_equal result.age, @contact.age
+    assert_equal Time.parse(result.created_at), @contact.created_at
+    assert_equal result.awesome, @contact.awesome
+    assert_equal result.preferences, @contact.preferences
   end
 
   test "custom as_json should be honored when generating json" do
-    def @contact.as_json(options); { :name => name, :created_at => created_at }; end
+    def @contact.as_json(options); { name: name, created_at: created_at }; end
     json = @contact.to_json
 
     assert_match %r{"name":"Konata Izumi"}, json
@@ -209,7 +200,7 @@ def @contact.as_json(options); { :name => name, :created_at => created_at }; end
   end
 
   test "custom as_json options should be extendible" do
-    def @contact.as_json(options = {}); super(options.merge(:only => [:name])); end
+    def @contact.as_json(options = {}); super(options.merge(only: [:name])); end
     json = @contact.to_json
 
     assert_match %r{"name":"Konata Izumi"}, json
@@ -217,5 +208,4 @@ def @contact.as_json(options = {}); super(options.merge(:only => [:name])); end
     assert_no_match %r{"awesome":}, json
     assert_no_match %r{"preferences":}, json
   end
-
 end

railties/lib/rails/generators/rails/app/templates/config/initializers/wrap_parameters.rb.tt

@@ -9,8 +9,8 @@ ActiveSupport.on_load(:action_controller) do
 end
 
 <%- unless options.skip_active_record? -%>
-# Disable root element in JSON by default.
-ActiveSupport.on_load(:active_record) do
-  self.include_root_in_json = false
-end
+# To enable root element in JSON for ActiveRecord objects.
+# ActiveSupport.on_load(:active_record) do
+#  self.include_root_in_json = true
+# end
 <%- end -%>