access to assigned relationship

Gemfile

@@ -11,5 +11,5 @@ gem 'addressable', '~> 2.2'
 gem "codeclimate-test-reporter", group: :test, require: nil
 
 group :development, :test do
-  gem 'byebug', platforms: [:mri_20, :mri_21, :mri_22]
+  gem 'byebug', '~> 10.0', platforms: [:mri_20, :mri_21, :mri_22]
 end

lib/json_api_client/associations/base_association.rb

@@ -21,6 +21,13 @@ def data(url)
       def from_result_set(result_set)
         result_set.to_a
       end
+
+      def load_records(data)
+        data.map do |d|
+          record_class = Utils.compute_type(klass, d["type"].classify)
+          record_class.load id: d["id"]
+        end
+      end
     end
   end
 end

lib/json_api_client/associations/has_one.rb

@@ -5,7 +5,12 @@ class Association < BaseAssociation
         def from_result_set(result_set)
           result_set.first
         end
+
+        def load_records(data)
+          record_class = Utils.compute_type(klass, data["type"].classify)
+          record_class.load id: data["id"]
+        end
       end
     end
   end
-end
+end

lib/json_api_client/resource.rb

@@ -537,7 +537,11 @@ def included_data_for(name, relationship_definition)
     def relationship_data_for(name, relationship_definition)
       # look in included data
       if relationship_definition.key?("data")
-        return included_data_for(name, relationship_definition)
+        if relationships.attribute_changed?(name)
+          return relation_objects_for(name, relationship_definition)
+        else
+          return included_data_for(name, relationship_definition)
+        end
       end
 
       url = relationship_definition["links"]["related"]
@@ -548,6 +552,13 @@ def relationship_data_for(name, relationship_definition)
       nil
     end
 
+    def relation_objects_for(name, relationship_definition)
+      data = relationship_definition["data"]
+      assoc = association_for(name)
+      return if data.nil? || assoc.nil?
+      assoc.load_records(data)
+    end
+
     def method_missing(method, *args)
       relationship_definition = relationship_definition_for(method)
 

test/unit/creation_test.rb

@@ -18,6 +18,16 @@ def after_create_method
   class Author < TestResource
   end
 
+  class User < TestResource
+    has_one :skill_level
+
+    properties :first_name, type: :string
+  end
+
+  class SkillLevel < TestResource
+    property :title, type: :string
+  end
+
   def stub_simple_creation
     stub_request(:post, "http://example.com/articles")
       .with(headers: {content_type: "application/vnd.api+json", accept: "application/vnd.api+json"}, body: {
@@ -341,4 +351,40 @@ def test_create_with_custom_type
     assert_equal '1', file.id
   end
 
+  def test_access_loaded_relationship_instance
+    stub_request(:get, 'http://example.com/skill_levels/1')
+        .to_return(headers: {content_type: 'application/vnd.api+json'}, body: {
+            data: {
+                type: 'skill_levels',
+                id: '1',
+                attributes: {
+                    title: 'newbie'
+                }
+            }
+        }.to_json)
+
+    stub_request(:get, 'http://example.com/skill_levels/2')
+        .to_return(headers: {content_type: 'application/vnd.api+json'}, body: {
+            data: {
+                type: 'skill_levels',
+                id: '2',
+                attributes: {
+                    title: 'pro'
+                }
+            }
+        }.to_json)
+
+    skill_level = SkillLevel.find(1).first
+    user = User.new(first_name: 'Joe', relationships: { skill_level: skill_level })
+
+    assert_equal ({'data'=>{'type'=>'skill_levels', 'id'=>'1'}}), user.relationships.skill_level
+    assert_kind_of SkillLevel, user.skill_level
+    assert_equal '1', user.skill_level.id
+    # test that object is cached and not recreated each time
+    assert_equal user.skill_level.object_id, user.skill_level.object_id
+
+    user.skill_level = SkillLevel.find(2).first
+    assert_equal '2', user.skill_level.id
+  end
+
 end