Fixes virtual value not being used

lib/active_model/serializer/adapter/json_api.rb

@@ -49,7 +49,7 @@ def add_relationships(resource, name, serializers)
 
         def add_relationship(resource, name, serializer, val=nil)
           resource[:relationships] ||= {}
-          resource[:relationships][name] = { data: nil }
+          resource[:relationships][name] = { data: val }
 
           if serializer && serializer.object
             resource[:relationships][name][:data] = { type: serializer.type, id: serializer.id.to_s }

test/adapter/json_api/has_many_test.rb

@@ -31,6 +31,8 @@ def setup
             @post.tags = [@tag]
             @serializer = PostSerializer.new(@post)
             @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer)
+
+            @virtual_value = VirtualValue.new(id: 1)
           end
 
           def test_includes_comment_ids
@@ -115,7 +117,23 @@ def test_has_many_with_no_serializer
                 id: "1",
                 type: "posts",
                 relationships: {
-                  tags: { data: nil }
+                  tags: { data: [@tag.as_json]}
+                }
+              }
+            }, adapter.serializable_hash)
+          end
+
+          def test_has_many_with_virtual_value
+            serializer = VirtualValueSerializer.new(@virtual_value)
+            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer)
+
+            assert_equal({
+              data: {
+                id: "1",
+                type: "virtual_values",
+                relationships: {
+                  maker: {data: {id: 1}},
+                  reviews: {data: [{id: 1}, {id: 2}]}
                 }
               }
             }, adapter.serializable_hash)

test/adapter/json_api/has_one_test.rb

@@ -25,6 +25,8 @@ def setup
             @author.posts = []
             @author.roles = []
 
+            @virtual_value = VirtualValue.new(id: 1)
+
             @serializer = AuthorSerializer.new(@author)
             @adapter = ActiveModel::Serializer::Adapter::JsonApi.new(@serializer, include: 'bio,posts')
           end
@@ -54,6 +56,24 @@ def test_includes_linked_bio
 
             assert_equal(expected, @adapter.serializable_hash[:included])
           end
+
+          def test_has_one_with_virtual_value
+            serializer = VirtualValueSerializer.new(@virtual_value)
+            adapter = ActiveModel::Serializer::Adapter::JsonApi.new(serializer)
+
+            expected = {
+              data: {
+                id: "1",
+                type: "virtual_values",
+                relationships: {
+                  maker: {data: {id: 1}},
+                  reviews: {data: [{id: 1}, {id: 2}]}
+                }
+              }
+            }
+
+            assert_equal(expected, adapter.serializable_hash)
+          end
         end
       end
     end

test/fixtures/poro.rb

@@ -77,6 +77,7 @@ class ProfilePreviewSerializer < ActiveModel::Serializer
 Location = Class.new(Model)
 Place    = Class.new(Model)
 Tag      = Class.new(Model)
+VirtualValue = Class.new(Model)
 Comment  = Class.new(Model) do
   # Uses a custom non-time-based cache key
   def cache_key
@@ -231,6 +232,19 @@ def self.root_name
   has_many :tags
 end
 
+VirtualValueSerializer = Class.new(ActiveModel::Serializer) do
+  attributes :id
+
+  has_many :reviews, virtual_value: [{id: 1}, {id: 2}]
+  has_one :maker, virtual_value: {id: 1}
+
+  def reviews
+  end
+
+  def maker
+  end
+end
+
 Spam::UnrelatedLinkSerializer = Class.new(ActiveModel::Serializer) do
   attributes :id
 end