Odoo 12 Development Essentials - Fourth Edition

Adding business logic

Previously, we added a button to the Book Form section to check whether the ISBN is valid. Modern ISBNs have 13 digits, where the last one is a check digit computed from the first 12.

There is little point getting into the details of the algorithm used, so here is a Python function that implements this validation. It should be added inside the class Book(...) object, before the name field:

    @api.multi    def _check_isbn(self):        self.ensure_one()        digits = [int(x) for x in self.isbn if x.isdigit()]        if len(digits) == 13:            ponderations = [1, 3] * 6            terms = [a * b for a, b in zip(digits[:12], ponderations)]            remain = sum(terms) % 10             check = 10 - remain if remain != 0 else 0            return digits[-1] == check

The button_check_isbn() method ...