Merge pull request #710 from olleolleolle/feature/belongs-to-as-has-one-alias

Add belongs_to as DSL warning wrapper to has_one to help beginners

Author: lgebhardt

lib/jsonapi/resource.rb

@@ -437,6 +437,15 @@ def relationship(*attrs)
       def has_one(*attrs)
         _add_relationship(Relationship::ToOne, *attrs)
       end
+      
+      def belongs_to(*attrs)
+        ActiveSupport::Deprecation.warn "In #{name} you exposed a `has_one` relationship "\
+                                        " using the `belongs_to` class method. We think `has_one`" \
+                                        " is more appropriate. If you know what you're doing," \
+                                        " and don't want to see this warning again, override the" \
+                                        " `belongs_to` class method on your resource."
+        _add_relationship(Relationship::ToOne, *attrs)
+      end
 
       def has_many(*attrs)
         _add_relationship(Relationship::ToMany, *attrs)

test/unit/jsonapi_request/jsonapi_request_test.rb

@@ -4,7 +4,7 @@ class CatResource < JSONAPI::Resource
   attribute :name
   attribute :breed
 
-  has_one :mother, class_name: 'Cat'
+  belongs_to :mother, class_name: 'Cat'
   has_one :father, class_name: 'Cat'
 
   filters :name