SGQR payload generator

gistfile1.txt

from pycrc.algorithms import Crc

def generate_qr_string(uen, is_uen, company_name, transaction_id, amount, editable, expiry):

    merchant_values = [
        '00' + str(len('SG.PAYNOW')).zfill(2) + 'SG.PAYNOW',
        '01' + str(len(is_uen)).zfill(2) + is_uen,  # 0 for mobile, 2 for UEN
        '02' + str(len(uen)).zfill(2) + uen,  # uen / mobile number
        '03' + str(len(editable)).zfill(2) + editable,  # 1 = editable, 0 = not editable
        '04' + str(len(expiry)).zfill(2) + expiry,  # YYYYMMDD
    ]

    merchant_info = ''.join(merchant_values)

    additional_value = ['01' + str(len(transaction_id)).zfill(2) + transaction_id]  # bill/ref number
    additional_info = ''.join(additional_value)

    values = [
        '00' + str(len('01')).zfill(2) + '01',
        '01' + str(len('12')).zfill(2) + '12',
        '26' + str(len(merchant_info)).zfill(2) + merchant_info,
        '52' + str(len('0000')).zfill(2) + '0000',  # merchant category code, not used
        '53' + str(len('702')).zfill(2) + '702',  # SGD currency
        '54' + str(len(amount)).zfill(2) + amount,  # transaction amount
        '58' + str(len('SG')).zfill(2) + 'SG',  # 2 letter country code
        '59' + str(len(company_name)).zfill(2) + company_name,  # company name
        '60' + str(len('Singapore')).zfill(2) + 'Singapore',  # Merchant City
        '62' + str(len(additional_info)).zfill(2) + additional_info,
        '6304'
    ]

    qr_string = ''.join(values)

    # Sample code from https://pycrc.org
    crc = Crc(width=16, poly=0x1021,
              reflect_in=False, xor_in=0xffff,
              reflect_out=False, xor_out=0x0000)

    my_crc = crc.bit_by_bit_fast(qr_string)          # calculate the CRC, using the bit-by-bit-fast algorithm.
    crc_data_upper = ('{:04X}'.format(my_crc))

    final_string = qr_string + crc_data_upper

    return final_string
# end def