old_contents: # -*- coding: utf8 -*-
  from flask.ext.restplus import fields as basefields
  
  class Date(basefields.BaseField):
      __schema_type__ = 'date'
      __schema_format__ = None
  
      def schema(self):
          return {
              'type': self.__schema_type__,
              'format': self.__schema_format__,
              'title': self.title,
              'description': self.description,
              'readOnly': self.readonly,
          }
  
      def format(self):
          return self.isoformat()
  
      def output(self, key, value):
          if isinstance(value, dict):
              return value[key]
          value = value[key]
          if isinstance(value, str):
              return value
          date = getattr(value, key)
          return date.isoformat() if date else None
  
new_contents: # -*- coding: utf8 -*-
  from flask.ext.restplus import fields as basefields
  
  class Date(basefields.BaseField):
      __schema_type__ = 'date'
      __schema_format__ = None
  
      def schema(self):
          return {
              'type': self.__schema_type__,
              'format': self.__schema_format__,
              'title': self.title,
              'description': self.description,
              'readOnly': self.readonly,
          }
  
      def format(self):
          return self.isoformat()
  
      def output(self, key, value):
          if isinstance(value, dict):
              value = value[key]
          if isinstance(value, str):
              return value
          date = getattr(value, key)
          return date.isoformat() if date else None
  
subject: fix date