Ensure relationship renders independent of fields (#98)

Explained jsonapi-rb/jsonapi-serializable#102

Author: richmolj

lib/jsonapi_compliable.rb

@@ -32,6 +32,14 @@
   require 'jsonapi/serializable'
 end
 
+# Temporary fix until fixed upstream
+# https://github.com/jsonapi-rb/jsonapi-serializable/pull/102
+JSONAPI::Serializable::Resource.class_eval do
+  def requested_relationships(fields)
+    @_relationships
+  end
+end
+
 require "jsonapi_compliable/extensions/extra_attribute"
 require "jsonapi_compliable/extensions/boolean_attribute"
 require "jsonapi_compliable/extensions/temp_id"

spec/integration/rails/finders_spec.rb

@@ -193,6 +193,16 @@ def json
       expect(json_included_types).to match_array(%w(books genres))
     end
 
+    context 'when passing sparse fieldsets on primary data' do
+      context 'and sideloading' do
+        it 'is able to sideload without adding the field' do
+          get :index, params: { fields: { authors: 'first_name' }, include: 'books' }
+          expect(json['data'][0]['relationships']).to be_present
+          expect(json_included_types).to match_array(%w(books))
+        end
+      end
+    end
+
     context 'sideloading has_many' do
       # TODO: may want to blow up here, only for index action
       it 'allows pagination of sideloaded resource' do