With our team, we would like to implement a feature where the user is warned whenever the record he/she is updating have also been updated by one of his collegue since he/she opened the record.

We dug into the source code because we did not find any official documentation, only some module that did not fit our Odoo version (11).

We found in the file /odoo/odoo/models.py the method def _check_concurrency(self): with the following code:

    @api.multi
    def _check_concurrency(self):
        if not (self._log_access and self._context.get(self.CONCURRENCY_CHECK_FIELD)):
            return
        check_clause = "(id = %s AND %s < COALESCE(write_date, create_date, (now() at time zone 'UTC'))::timestamp)"
        for sub_ids in self._cr.split_for_in_conditions(self.ids):
            nclauses = 0
            params = []
            for id in sub_ids:
                id_ref = "%s,%s" % (self._name, id)
                update_date = self._context[self.CONCURRENCY_CHECK_FIELD].pop(id_ref, None)
                if update_date:
                    nclauses += 1
                    params.extend([id, update_date])
            if not nclauses:
                continue
            query = "SELECT id FROM %s WHERE %s" % (self._table, " OR ".join([check_clause] * nclauses))
            self._cr.execute(query, tuple(params))
            res = self._cr.fetchone()
            if res:
                # mention the first one only to keep the error message readable
                raise ValidationError(_('A document was modified since you last viewed it (%s:%d)') % (self._description, res[0]))

=> This method is called before any "write". It compares :

• the '__last_update' value of the record at the time of 'write'

• with a value of '__last_update' get from the context, which therefore should have been set in the 'context' beforehand

** PROBLEM ** We did not find anywhere in the code (python or javascript) the value set in the context => NOTHING HAPPENS ! THe function returns from the beginning.

When we tried to hardcode it in the context, the function check_concurrency seems to work properly.

QUESTION

Does anyone one know where the __last_update is set or SHOULD BE set in the context ? And how ? I would e.g. imagine setting it somehow when clicking on edit button of a record ??? Or at read time ??