Implement Serializer's root

lib/active_model/serializer.rb

@@ -5,7 +5,16 @@ module ActiveModel
         base._attributes = {}
       end
 
-      attr_accessor :_attributes
+      attr_accessor :_root, :_attributes
+
+      def root(root)
+        @_root = root
+      end
+      alias root= root
+
+      def root_name
+        name.demodulize.underscore.sub(/_serializer$/, '') if name
+      end
 
       def attributes(*attrs)
         @_attributes = attrs.map(&:to_s)
@@ -18,10 +27,12 @@ module ActiveModel
       end
     end
 
-    def initialize(object)
+    def initialize(object, options={})
       @object = object
+      @root   = options[:root] || self.class._root
+      @root   = self.class.root_name if @root == true
     end
-    attr_accessor :object
+    attr_accessor :object, :root
 
     alias read_attribute_for_serialization send
 
@@ -37,7 +48,11 @@ module ActiveModel
     end
 
     def as_json(options={})
-      serializable_hash
+      if root = options[:root] || self.root
+        { root.to_s => serializable_hash }
+      else
+        serializable_hash
+      end
     end
   end
 end

test/serializer/root_test.rb

@@ -0,0 +1,103 @@
+require 'newbase/test_helper'
+require 'newbase/active_model/serializer'
+
+module SerializerTest
+  module Root
+    class Model
+      def initialize(hash={})
+        @attributes = hash
+      end
+
+      def read_attribute_for_serialization(name)
+        @attributes[name]
+      end
+    end
+
+    class RootAsOptionTest < ActiveModel::TestCase
+      class ModelSerializer < ActiveModel::Serializer
+        attributes :attr1, :attr2
+      end
+      ModelSerializer.root = true
+
+      def setup
+        @model = Model.new({ :attr1 => 'value1', :attr2 => 'value2', :attr3 => 'value3' })
+        @serializer = ModelSerializer.new(@model, root: 'initialize')
+      end
+
+      def test_root_is_not_displayed_using_serializable_hash
+        assert_equal({
+          'attr1' => 'value1', 'attr2' => 'value2'
+        }, @serializer.serializable_hash)
+      end
+
+      def test_root_using_as_json
+        assert_equal({
+          'initialize' => {
+            'attr1' => 'value1', 'attr2' => 'value2'
+          }
+        }, @serializer.as_json)
+      end
+
+      def test_root_from_serializer_name
+        @serializer = ModelSerializer.new(@model)
+
+        assert_equal({
+          'model' => {
+            'attr1' => 'value1', 'attr2' => 'value2'
+          }
+        }, @serializer.as_json)
+      end
+
+      def test_root_as_argument_takes_presedence
+        assert_equal({
+          'argument' => {
+            'attr1' => 'value1', 'attr2' => 'value2'
+          }
+        }, @serializer.as_json(root: 'argument'))
+      end
+    end
+
+    class RootInSerializerTest < ActiveModel::TestCase
+      class ModelSerializer < ActiveModel::Serializer
+        root :in_serializer
+        attributes :attr1, :attr2
+      end
+
+      def setup
+        model = Model.new({ :attr1 => 'value1', :attr2 => 'value2', :attr3 => 'value3' })
+        @serializer = ModelSerializer.new(model)
+        @rooted_serializer = ModelSerializer.new(model, root: :initialize)
+      end
+
+      def test_root_is_not_displayed_using_serializable_hash
+        assert_equal({
+          'attr1' => 'value1', 'attr2' => 'value2'
+        }, @serializer.serializable_hash)
+      end
+
+      def test_root_using_as_json
+        assert_equal({
+          'in_serializer' => {
+            'attr1' => 'value1', 'attr2' => 'value2'
+          }
+        }, @serializer.as_json)
+      end
+
+      def test_root_in_initializer_takes_precedence
+        assert_equal({
+          'initialize' => {
+            'attr1' => 'value1', 'attr2' => 'value2'
+          }
+        }, @rooted_serializer.as_json)
+      end
+
+      def test_root_as_argument_takes_precedence
+        assert_equal({
+          'argument' => {
+            'attr1' => 'value1', 'attr2' => 'value2'
+          }
+        }, @rooted_serializer.as_json(root: :argument))
+      end
+    end
+  end
+end