Store resource_type in local (Code Climate)

Author: gfmurphy

lib/graphiti/query.rb

@@ -48,9 +48,10 @@ def hash
         h[:sort] = sorts
         h[:page] = pagination
         if association?
+          resource_type = @resource.class.type
           h[:extra_fields] = {
-             @resource.class.type => extra_fields[@resource.class.type]
-           } if extra_fields.key?(@resource.class.type)
+             resource_type => extra_fields[resource_type]
+           } if extra_fields.key?(resource_type)
         else
           h[:fields] = fields
           h[:extra_fields] = extra_fields