Barcode validation script

Hi,

There is my script to check barcodes checksum. It calculates check digit for the following list of standarts at once: GTIN-8 (EAN-8), GTIN-12 (UPC), GTIN-13 (EAN-13), GTIN-14, GSIN and SSCC.

let barcodeShrinked := replace(barcode, " ", "");
let barcodeLength := length(barcodeShrinked);
let evenPositionDigitSum := 0;
let oddPositionDigitSum := 0;
if barcodeLength = 8 or barcodeLength = 12 or barcodeLength = 13 or barcodeLength = 14 or barcodeLength = 17 or barcodeLength = 18 then
let barcode := lpad(barcodeShrinked, 19, "0");
for i in range(0, 9) do
evenPositionDigitSum := evenPositionDigitSum + number(substr(barcode, i * 2, 1));
oddPositionDigitSum := oddPositionDigitSum + number(substr(barcode, i * 2 + 1, 1))
end;
let barcodeCheckSum := number(substr(barcode, 18, 1));
let resultSum := 3 * oddPositionDigitSum + evenPositionDigitSum;
let resultCheckSum := 0;
if resultSum != 10 * floor(resultSum / 10) then
resultCheckSum := 10 * floor(resultSum / 10) - resultSum + 10
else
void
end;
if barcodeCheckSum != resultCheckSum then
barcode_validation_message := "Wrong checksum"
else
barcode := barcodeShrinked;
barcode_validation_message := "Correct"
end
else
barcode_validation_message := "Wrong barcode"
end

This script runs each time I update "barcode" field. For comfort editing reason script understands optional spaces between digits — it will cut them off if the barcode is valid.

Unfortunately I didn't find the way to change field's background color, so I added an additional field "barcode_validation_message" to indicate out whether data in main field is correct or wrong.