[Answered ]-Get user's last message django-postman & Rest API

You can get the last message like this:

def get_lastmessage(self, obj):
    lastmsg = Message.objects.latest('sent_at')
    data = {'senderusername': obj.senderusername,
        'reciusername': obj.reciusername,
        'body': lastmsg.body
        'sent_at': lastmsg.sent_at
        'last_message': {
            'body': lastmsg.body
        }
    }
  
    return data