Include 'linked' member for json-api collections

.gitignore

@@ -16,4 +16,4 @@ test/tmp
 test/version_tmp
 tmp
 *.swp
-.ruby-version
+.ruby-version

lib/active_model/serializer/adapter/json_api.rb

@@ -5,22 +5,22 @@ class JsonApi < Adapter
         def initialize(serializer, options = {})
           super
           serializer.root = true
+          @hash = {}
+          @top = options.fetch(:top) { @hash }
         end
 
         def serializable_hash(options = {})
           @root = (options[:root] || serializer.json_key).to_s.pluralize.to_sym
-          @hash = {}
 
           if serializer.respond_to?(:each)
-            @hash[@root] = serializer.map{|s| self.class.new(s).serializable_hash[@root] }
+            @hash[@root] = serializer.map do |s|
+              self.class.new(s, options.merge(top: @top)).serializable_hash[@root]
+            end
           else
             @hash[@root] = attributes_for_serializer(serializer, {})
 
             serializer.each_association do |name, association, opts|
               @hash[@root][:links] ||= {}
-              unless options[:embed] == :ids
-                @hash[:linked] ||= {}
-              end
 
               if association.respond_to?(:each)
                 add_links(name, association, opts)
@@ -35,11 +35,13 @@ def serializable_hash(options = {})
 
         def add_links(name, serializers, options)
           @hash[@root][:links][name] ||= []
-          @hash[@root][:links][name] += serializers.map{|serializer| serializer.id.to_s }
+          @hash[@root][:links][name] += serializers.map { |serializer| serializer.id.to_s }
 
-          unless options[:embed] == :ids
-            @hash[:linked][name] ||= []
-            @hash[:linked][name] += serializers.map { |item| attributes_for_serializer(item, options) }
+          unless serializers.none? || options[:embed] == :ids
+            init_linked_for_resource(name)
+            serializers.each do |serializer|
+              add_linked(name, serializer, options)
+            end
           end
         end
 
@@ -48,19 +50,29 @@ def add_link(name, serializer, options)
 
           unless options[:embed] == :ids
             plural_name = name.to_s.pluralize.to_sym
-
-            @hash[:linked][plural_name] ||= []
-            @hash[:linked][plural_name].push attributes_for_serializer(serializer, options)
+            init_linked_for_resource(plural_name)
+            add_linked(plural_name, serializer, options)
           end
         end
 
+        def init_linked_for_resource(resource)
+          @top[:linked] ||= {}
+          @top[:linked][resource] ||= []
+        end
+
+        def add_linked(resource, serializer, options)
+          attrs = attributes_for_serializer(serializer, options)
+          @top[:linked][resource].push attrs unless @top[:linked][resource].include? attrs
+        end
+
         private
 
         def attributes_for_serializer(serializer, options)
           attributes = serializer.attributes(options)
           attributes[:id] = attributes[:id].to_s if attributes[:id]
           attributes
         end
+
       end
     end
   end

test/adapter/json_api/collection_test.rb

@@ -17,10 +17,23 @@ def setup
 
           def test_include_multiple_posts
             assert_equal([
-                           {title: "Hello!!", body: "Hello, world!!", id: "1", links: {comments: []}},
-                           {title: "New Post", body: "Body", id: "2", links: {comments: []}}
+                             {title: "Hello!!", body: "Hello, world!!", id: "1", links: {comments: []}},
+                             {title: "New Post", body: "Body", id: "2", links: {comments: []}}
                          ], @adapter.serializable_hash[:posts])
+            refute @adapter.serializable_hash.key?(:linked)
           end
+
+          def test_include_multiple_posts_and_linked
+            @first_comment = Comment.new(id: 1, body: 'ZOMG A COMMENT')
+            @second_comment = Comment.new(id: 2, body: 'ZOMG ANOTHER COMMENT')
+            @first_post.comments = [@first_comment, @second_comment]
+            assert_equal([
+                           { title: "Hello!!", body: "Hello, world!!", id: "1", links: { comments: ['1', '2'] } },
+                           { title: "New Post", body: "Body", id: "2", links: { comments: [] } }
+                         ], @adapter.serializable_hash[:posts])
+            assert_equal({ :comments => [{ :id => "1", :body => "ZOMG A COMMENT" }, { :id => "2", :body => "ZOMG ANOTHER COMMENT" }] }, @adapter.serializable_hash[:linked])
+          end
+
         end
       end
     end