55 lines
2.2 KiB
Python
55 lines
2.2 KiB
Python
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# -*- coding: utf-8 -*-
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# Part of Odoo. See LICENSE file for full copyright and licensing details.
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import re
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def get_barcode_check_digit(numeric_barcode):
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""" Computes and returns the barcode check digit. The used algorithm
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follows the GTIN specifications and can be used by all compatible
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barcode nomenclature, like as EAN-8, EAN-12 (UPC-A) or EAN-13.
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https://www.gs1.org/sites/default/files/docs/barcodes/GS1_General_Specifications.pdf
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https://www.gs1.org/services/how-calculate-check-digit-manually
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:param numeric_barcode: the barcode to verify/recompute the check digit
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:type numeric_barcode: str
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:return: the number corresponding to the right check digit
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:rtype: int
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"""
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# Multiply value of each position by
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# N1 N2 N3 N4 N5 N6 N7 N8 N9 N10 N11 N12 N13 N14 N15 N16 N17 N18
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# x3 X1 x3 x1 x3 x1 x3 x1 x3 x1 x3 x1 x3 x1 x3 x1 x3 CHECKSUM
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oddsum = evensum = 0
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code = numeric_barcode[-2::-1] # Remove the check digit and reverse the barcode.
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# The CHECKSUM digit is removed because it will be recomputed and it must not interfer with
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# the computation. Also, the barcode is inverted, so the barcode length doesn't matter.
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# Otherwise, the digits' group (even or odd) could be different according to the barcode length.
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for i, digit in enumerate(code):
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if i % 2 == 0:
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evensum += int(digit)
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else:
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oddsum += int(digit)
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total = evensum * 3 + oddsum
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return (10 - total % 10) % 10
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def check_barcode_encoding(barcode, encoding):
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""" Checks if the given barcode is correctly encoded.
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:return: True if the barcode string is encoded with the provided encoding.
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:rtype: bool
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"""
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encoding = encoding.lower()
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if encoding == "any":
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return True
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barcode_sizes = {
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'ean8': 8,
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'ean13': 13,
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'gtin14': 14,
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'upca': 12,
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'sscc': 18,
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}
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barcode_size = barcode_sizes[encoding]
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return (encoding != 'ean13' or barcode[0] != '0') \
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and len(barcode) == barcode_size \
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and re.match(r"^\d+$", barcode) \
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and get_barcode_check_digit(barcode) == int(barcode[-1])
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