Ensure correct dirty tracking when boolean attribute is false

Author: leonvogt

lib/attr_json/record.rb

@@ -65,7 +65,7 @@ def attr_json_sync_to_rails_attributes
             attr_name     = attribute_def.name
             value         = container_value[attribute_def.store_key]
 
-            if value
+            unless value.nil?
               # TODO, can we just make this use the setter?
               write_attribute(attr_name, value)