Add initial support for embed API

activemodel/lib/active_model/serializer.rb

@@ -21,7 +21,7 @@ def serialize(collection, scope)
 
         def serialize_ids(collection, scope)
           # use named scopes if they are present
-          return collection.ids if collection.respond_to?(:ids)
+          #return collection.ids if collection.respond_to?(:ids)
 
           collection.map do |item|
             item.read_attribute_for_serialization(:id)
@@ -47,6 +47,9 @@ def serialize_ids(object, scope)
     self._associations = []
 
     class_attribute :_root
+    class_attribute :_embed
+    self._embed = :objects
+    class_attribute :_root_embed
 
     class << self
       def attributes(*attrs)
@@ -73,6 +76,11 @@ def has_one(*attrs)
         associate(Associations::HasOne, attrs)
       end
 
+      def embed(type, options={})
+        self._embed = type
+        self._root_embed = true if options[:include]
+      end
+
       def root(name)
         self._root = name
       end
@@ -97,14 +105,22 @@ def initialize(object, scope)
 
     def as_json(*)
       if _root
-        { _root => serializable_hash }
+        hash = { _root => serializable_hash }
+        hash.merge!(associations) if _root_embed
+        hash
       else
         serializable_hash
       end
     end
 
     def serializable_hash
-      attributes.merge(associations)
+      if _embed == :ids
+        attributes.merge(association_ids)
+      elsif _embed == :objects
+        attributes.merge(associations)
+      else
+        attributes
+      end
     end
 
     def associations

activemodel/test/cases/serializer_test.rb

@@ -226,10 +226,12 @@ def post_serializer(type)
       attributes :title, :body
       has_many :comments, :serializer => CommentSerializer
 
-      define_method :serializable_hash do
-        post_hash = attributes
-        post_hash.merge!(send(type))
-        post_hash
+      if type != :super
+        define_method :serializable_hash do
+          post_hash = attributes
+          post_hash.merge!(send(type))
+          post_hash
+        end
       end
     end
   end
@@ -325,4 +327,80 @@ def test_false_root
     serializer = Class.new(serializer)
     assert_equal({ :author => nil }, serializer.new(blog, user).as_json)
   end
+
+  def test_embed_ids
+    serializer = post_serializer(:super)
+
+    serializer.class_eval do
+      root :post
+      embed :ids
+    end
+
+    post = Post.new(:title => "New Post", :body => "Body of new post", :email => "[email protected]")
+    comments = [Comment.new(:title => "Comment1", :id => 1), Comment.new(:title => "Comment2", :id => 2)]
+    post.comments = comments
+
+    serializer = serializer.new(post, nil)
+
+    assert_equal({
+      :post => {
+        :title => "New Post",
+        :body => "Body of new post",
+        :comments => [1, 2]
+      }
+    }, serializer.as_json)
+  end
+
+  def test_embed_ids_include_true
+    serializer = post_serializer(:super)
+
+    serializer.class_eval do
+      root :post
+      embed :ids, :include => true
+    end
+
+    post = Post.new(:title => "New Post", :body => "Body of new post", :email => "[email protected]")
+    comments = [Comment.new(:title => "Comment1", :id => 1), Comment.new(:title => "Comment2", :id => 2)]
+    post.comments = comments
+
+    serializer = serializer.new(post, nil)
+
+    assert_equal({
+      :post => {
+        :title => "New Post",
+        :body => "Body of new post",
+        :comments => [1, 2]
+      },
+      :comments => [
+        { :title => "Comment1" },
+        { :title => "Comment2" }
+      ]
+    }, serializer.as_json)
+  end
+
+  def test_embed_objects
+    serializer = post_serializer(:super)
+
+    serializer.class_eval do
+      root :post
+      embed :objects
+    end
+
+    post = Post.new(:title => "New Post", :body => "Body of new post", :email => "[email protected]")
+    comments = [Comment.new(:title => "Comment1", :id => 1), Comment.new(:title => "Comment2", :id => 2)]
+    post.comments = comments
+
+    serializer = serializer.new(post, nil)
+
+    assert_equal({
+      :post => {
+        :title => "New Post",
+        :body => "Body of new post",
+        :comments => [
+          { :title => "Comment1" },
+          { :title => "Comment2" }
+        ]
+      }
+    }, serializer.as_json)
+  end
 end