This is a custom Scalar type. This DateTime Scalar can be formatted into anything the consumer needs it to be.

Graphene_Formatted_DateTime.py

# -*- coding: utf-8 -*-
import datetime

import graphene
from graphene.types.datetime import DateTime


class FormattedDateTime(DateTime):
    """
    This is a custom Scalar type. This DateTime Scalar can be formatted into 
    anything the consumer needs it to be.
    """
    __format_description__ = """

    Default is in [iso8601](https://en.wikipedia.org/wiki/ISO_8601) format.

     ====== ================================================================================================ ========================== 
      Code                                              Meaning                                                       Example           
     ====== ================================================================================================ ========================== 
      %a     Weekday as locale’s abbreviated name.                                                            Mon                       
      %A     Weekday as locale’s full name.                                                                   Monday                    
      %w     Weekday as a decimal number, where 0 is Sunday and 6 is Saturday.                                1                         
      %d     Day of the month as a zero-padded decimal number.                                                30                        
      %-d    Day of the month as a decimal number. (Platform specific)                                        30                        
      %b     Month as locale’s abbreviated name.                                                              Sep                       
      %B     Month as locale’s full name.                                                                     September                 
      %m     Month as a zero-padded decimal number.                                                           9                         
      %-m    Month as a decimal number. (Platform specific)                                                   9                         
      %y     Year without century as a zero-padded decimal number.                                            13                        
      %Y     Year with century as a decimal number.                                                           2013                      
      %H     Hour (24-hour clock) as a zero-padded decimal number.                                            7                         
      %-H    Hour (24-hour clock) as a decimal number. (Platform specific)                                    7                         
      %I     Hour (12-hour clock) as a zero-padded decimal number.                                            7                         
      %-I    Hour (12-hour clock) as a decimal number. (Platform specific)                                    7                         
      %p     Locale’s equivalent of either AM or PM.                                                          AM                        
      %M     Minute as a zero-padded decimal number.                                                          6                         
      %-M    Minute as a decimal number. (Platform specific)                                                  6                         
      %S     Second as a zero-padded decimal number.                                                          5                         
      %-S    Second as a decimal number. (Platform specific)                                                  5                         
      %f     Microsecond as a decimal number, zero-padded on the left.                                        0                         
      %z     UTC offset in the form +HHMM or -HHMM (empty string if the the object is naive).                                           
      %Z     Time zone name (empty string if the object is naive).                                                                      
      %j     Day of the year as a zero-padded decimal number.                                                 273                       
      %-j    Day of the year as a decimal number. (Platform specific)                                         273                       
      %U     Week number of the year (Sunday as the first day of the week) as a zero padded decimal number.   39                        
      %W     Week number of the year (Monday as the first day of the week) as a decimal number.               39                        
      %c     Locale’s appropriate date and time representation.                                               Mon Sep 30 07:06:05 2013  
      %x     Locale’s appropriate date representation.                                                        09/30/13                  
      %X     Locale’s appropriate time representation.                                                        7:06:05                   
      %%     A literal '%' character.                                                                         %                         
     ====== ================================================================================================ ========================== 

    Please see [Strftime.org](http://strftime.org/) for more details.
    """

    def __init__(self, *args, **kwargs):
        kwargs['fmt'] = graphene.Argument(
            graphene.String,
            description='The format of the DateTime you want be returned.' +
                        self.__format_description__)
        kwargs['tz'] = graphene.Argument(
            graphene.String,
            description='The Time Zone you want the DateTime to be in.')
        super().__init__(*args, **kwargs)

    @staticmethod
    def serialize(dt):
        if isinstance(dt, (datetime.datetime, datetime.date)):
            return dt.isoformat()
        return dt

    
 # sample query
"""
{
   me {
     username
     givenName
     familyName
     email
     createdAt(fmt: "Registred on %a %d, %m %Y %H:%M%:S", tz='JST')
     updatedAt(fmt: "Updated on %a %d, %m %Y %H:%M%:S", tz='JST')
  }
}
"""