code: def value_to_db(self, value):
          
          assert isinstance(value, datetime.datetime)
  
          try:
              value = value - datetime.datetime(1970, 1, 1)
          except OverflowError:
              raise tldap.exceptions.ValidationError("is too big a date")
  
          value = value.seconds + value.days * 24 * 3600
          value = str(value).encode("utf_8")
  
          return value
docs: Returns field's single value prepared for saving into a database.