views.py file

def get_pdf_file(request, customer_id, sys_type):
    sys_type = customer_id
    area = "pdf"
    site_credit = site_credit1
    time_now = timezone.now()
    customers = get_object_or_404(CustomerInfo, pk=customer_id)

    due_taka_track = customers.duetaka_set.all()

    if due_taka_track == None:
        due_taka_track = 0

    unpaid_taka = int(customers.customer_price -
                      customers.customer_due_taka_info)
    due_taka_track = customers.duetaka_set.all()

    sum_cost_taka = due_taka_track.aggregate(
        sp=Sum('customer_due')).get('sp', 0)

    if sum_cost_taka == None:
        sum_cost_taka = 0
    total_paid_taka = sum_cost_taka + customers.customer_due_taka_info

    payment_status = 'complete'
    payment_message = ' '
    remain_taka='Full Paid '
    remain_msg=''


    if customers.customer_due_taka_info < customers.customer_price:
        payment_status = 'incomplete'
        payment_message = 'সম্পূর্ন টাকা পরিষোধ করা হয়নি'
        remain_msg='টাকা বাকী আছে'
        baki_ase="পাওনা আছে "

        remain_taka = customers.customer_price - customers.customer_due_taka_info



    context = {'customers': customers,
    'sys_type': sys_type,
    'area': area,
    'site_credit': site_credit,
    'site_name': 'Moon Telecom',
    'sys_type': sys_type,
    'due_taka_track': due_taka_track,
    'total_paid_taka': total_paid_taka,
    'payment_message': payment_message,
    'time_now': time_now,
    'unpaid_taka': unpaid_taka,
    'payment_message': payment_message,
    'remain_taka': remain_taka,
    'sum_cost_taka': sum_cost_taka,
    'remain_msg': remain_msg}

    html_string = render_to_string('shop/pdf_invoice.html', context).encode(encoding="UTF-8")
    response = HttpResponse(content_type='application/pdf')

    response['Content-Disposition'] = 'inline; filename=invoice' + \
        str(customers.id)+customers.customer_uid + customers.customer_name + '.pdf'

    HTML(string=html_string).write_pdf(response)
    return response