How do you associate a user with a payment when using M-Pesa express in Python Django?

Question

The response body on the call back is usually:

{
    "Body":
    {
        "stkCallback":
        {
            "MerchantRequestID": "21605-295434-4",
            "CheckoutRequestID": "ws_CO_04112017184930742",
            "ResultCode": 0,
            "ResultDesc": "The service request is processed successfully.",
            "CallbackMetadata":
            {
                "Item":
                [
                    {
                        "Name": "Amount",
                        "Value": 500
                    },
                    {
                        "Name": "MpesaReceiptNumber",
                        "Value": "WHAkLK451H35OP"
                    },
                    {
                        "Name": "Balance"
                    },
                    {
                        "Name": "TransactionDate",
                        "Value": 20171104184944
                    },
                    {
                        "Name": "PhoneNumber",
                        "Value": 254710549039
                    }
                ]
            }
        }
    }
}

This is my callback URL, which works fine and saves the data in a model. How can you associate a user with a payment once the response is received and saved in a general model not associated with any user?

@csrf_exempt
def callbackurl(request):
    if request.method == 'POST':
        m_body =request.body.decode('utf-8')
        mpesa_payment = json.loads(m_body)
        payment = StatusPayment(
            phoneno=mpesa_payment['Body']['stkCallback']['CallbackMetadata']['Item'][4]['Value'],
            transcode=mpesa_payment['Body']['stkCallback']['CallbackMetadata']['Item'][1]['Value'],
        )
        payment.save()
        context = {
             "ResultCode": 0,
             "ResultDesc": "Accepted"
        }
        return JsonResponse(dict(context))`