South African ID number Validation for openERP

IDvalidation.py

# info from http://geekswithblogs.net/willemf/archive/2005/10/30/58561.aspx

    def _id_check(self, cr, uid, ids, context=None):
        obj = self.browse(cr, uid, ids[0], context=context)
        if obj and obj.idnumber:
            idnum = str(obj.idnumber)
            if len(idnum) != 13:
                return False
            checksum1 = 0
            checksum2 = ""
            checksum3 = 0
            for p, ch in enumerate(idnum):
                pos = p+1
                if pos % 2 and pos != 13:
                    checksum1 += int(ch)
                if not (pos % 2):
                    checksum2 += ch
            checksum2 = int(checksum2) * 2
            for p, ch in enumerate(str(checksum2)):
                checksum3 += int(ch)
            checksum3 += checksum1
            if (10 - (checksum3 % 10)) != (int(idnum) % 10): # compare last digits
                return False
        return True

    _constraints = [
        (_id_check, 'Invalid SA ID number', ['idnumber'])
    ]