Add type when association name is different than objects type

lib/active_model/serializer/adapter/json_api.rb

@@ -34,8 +34,18 @@ module ActiveModel
         end
 
         def add_links(name, serializers, options)
-          @hash[@root][:links][name] ||= []
-          @hash[@root][:links][name] += serializers.map{|serializer| serializer.id.to_s }
+          if serializers.first
+            type = serializers.first.object.class.to_s.underscore.pluralize
+          end
+          if name.to_s == type || !type
+            @hash[@root][:links][name] ||= []
+            @hash[@root][:links][name] += serializers.map{|serializer| serializer.id.to_s }
+          else
+            @hash[@root][:links][name] ||= {}
+            @hash[@root][:links][name][:type] = type
+            @hash[@root][:links][name][:ids] ||= []
+            @hash[@root][:links][name][:ids] += serializers.map{|serializer| serializer.id.to_s }
+          end
 
           unless options[:embed] == :ids
             @hash[:linked][name] ||= []
@@ -45,7 +55,14 @@ module ActiveModel
 
         def add_link(name, serializer, options)
           if serializer
-            @hash[@root][:links][name] = serializer.id.to_s
+            type = serializer.object.class.to_s.underscore
+            if name.to_s == type || !type
+              @hash[@root][:links][name] = serializer.id.to_s
+            else
+              @hash[@root][:links][name] ||= {}
+              @hash[@root][:links][name][:type] = type
+              @hash[@root][:links][name][:id] = serializer.id.to_s
+            end
 
             unless options[:embed] == :ids
               plural_name = name.to_s.pluralize.to_sym

test/adapter/json_api/belongs_to_test.rb

@@ -15,6 +15,9 @@ module ActiveModel
             @comment.post = @post
             @post.author = @author
             @anonymous_post.author = nil
+            @blog = Blog.new(id: 1, name: "My Blog!!")
+            @blog.writer = @author
+            @blog.articles = [@post, @anonymous_post]
 
             @serializer = CommentSerializer.new(@comment)
             @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer)
@@ -34,6 +37,12 @@ module ActiveModel
 
             assert_equal({comments: [], author: nil}, adapter.serializable_hash[:posts][:links])
           end
+
+          def test_include_type_for_association_when_is_different_than_name
+            serializer = BlogSerializer.new(@blog)
+            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer)
+            assert_equal({type: "author", id: "1"}, adapter.serializable_hash[:blogs][:links][:writer])
+          end
         end
       end
     end

test/adapter/json_api/has_many_test.rb

@@ -7,13 +7,16 @@ module ActiveModel
         class HasManyTest < Minitest::Test
           def setup
             @author = Author.new(id: 1, name: 'Steve K.')
-            @post = Post.new(title: 'New Post', body: 'Body')
+            @post = Post.new(id: 1, title: 'New Post', body: 'Body')
             @first_comment = Comment.new(id: 1, body: 'ZOMG A COMMENT')
             @second_comment = Comment.new(id: 2, body: 'ZOMG ANOTHER COMMENT')
             @post.comments = [@first_comment, @second_comment]
             @first_comment.post = @post
             @second_comment.post = @post
             @post.author = @author
+            @blog = Blog.new(id: 1, name: "My Blog!!")
+            @blog.writer = @author
+            @blog.articles = [@post]
 
             @serializer = PostSerializer.new(@post)
             @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer)
@@ -29,6 +32,12 @@ module ActiveModel
                            {id: "2", body: 'ZOMG ANOTHER COMMENT'}
                          ], @adapter.serializable_hash[:linked][:comments])
           end
+
+          def test_include_type_for_association_when_is_different_than_name
+            serializer = BlogSerializer.new(@blog)
+            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer)
+            assert_equal({type: "posts", ids: ["1"]}, adapter.serializable_hash[:blogs][:links][:articles])
+          end
         end
       end
     end

test/fixtures/poro.rb

@@ -38,6 +38,7 @@ end
 Post = Class.new(Model)
 Comment = Class.new(Model)
 Author = Class.new(Model)
+Blog = Class.new(Model)
 
 PostSerializer = Class.new(ActiveModel::Serializer) do
   attributes :title, :body, :id
@@ -58,3 +59,10 @@ AuthorSerializer = Class.new(ActiveModel::Serializer) do
 
   has_many :posts, embed: :ids
 end
+
+BlogSerializer = Class.new(ActiveModel::Serializer) do
+  attributes :id, :name
+
+  belongs_to :writer
+  has_many :articles
+end