wip

Author: bf4

lib/active_model/serializer/association.rb

@@ -34,6 +34,14 @@ def reflection
         reflection_options.fetch(:reflection)
       end
 
+      def to_many?
+        reflection.name == :has_many
+      end
+
+      def belongs_to?
+        reflection.foreign_key_on == :self
+      end
+
       def serializer
         association_value = reflection_options.fetch(:association_value_proc).call
         reflection_options.fetch(:serializer_proc).call(association_value, options.dup)

lib/active_model_serializers/adapter/json_api.rb

@@ -440,7 +440,7 @@ def relationships_for(serializer, requested_associations)
         serializer.associations(include_directive).each_with_object({}) do |association, hash|
           hash[association.key] = Relationship.new(
             serializer,
-            association.serializer,
+            association,
             instance_options,
             options: association.options,
             links: association.links,

lib/active_model_serializers/adapter/json_api/relationship.rb

@@ -6,12 +6,12 @@ class Relationship
         # {http://jsonapi.org/format/#document-links Document Links}
         # {http://jsonapi.org/format/#document-resource-object-linkage Document Resource Relationship Linkage}
         # {http://jsonapi.org/format/#document-meta Docment Meta}
-        def initialize(parent_serializer, serializer, serializable_resource_options, args = {})
+        def initialize(parent_serializer, association, serializable_resource_options, args = {})
           @object = parent_serializer.object
           @scope = parent_serializer.scope
           @association_options = args.fetch(:options, {})
           @serializable_resource_options = serializable_resource_options
-          @data = data_for(serializer)
+          @data = data_for(association)
           @links = args.fetch(:links, {}).each_with_object({}) do |(key, value), hash|
             result = Link.new(parent_serializer, value).as_json
             hash[key] = result if result
@@ -38,13 +38,23 @@ def as_json
 
         private
 
-        def data_for(serializer)
-          if serializer.respond_to?(:each)
+        def data_for(association)
+          if association.to_many?
+            serializer = association.serializer
             serializer.map { |s| ResourceIdentifier.new(s, serializable_resource_options).as_json }
           elsif association_options[:virtual_value]
             association_options[:virtual_value]
-          elsif serializer && serializer.object
-            ResourceIdentifier.new(serializer, serializable_resource_options).as_json
+          elsif association.belongs_to?
+            foreign_key = association.reflection.foreign_key
+            if @object.respond_to?(foreign_key)
+              {
+                id: @object.send(foreign_key),
+                type: association.reflection.type.to_s
+              }
+            else
+              serializer && serializer.object &&
+                ResourceIdentifier.new(serializer, serializable_resource_options).as_json
+            end
           end
         end
       end