set birthdate to user lang date_format if exist

partner_contact_birthdate/models/res_partner.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 # Copyright (C) 2014-2015  Grupo ESOC <www.grupoesoc.es>
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+from datetime import datetime
 from odoo import api, fields, models
 import logging
 
@@ -30,4 +31,9 @@ class ResPartner(models.Model):
     @api.one
     def _birthdate_inverse(self):
         """Convert the old Char date to the new Date format."""
-        self.birthdate_date = self.birthdate
+        try:
+            self.birthdate_date = self.birthdate
+        except ValueError:
+            date_format = self.env['res.lang']._lang_get(
+                self.env.lang).date_format
+            self.birthdate_date = datetime.strptime(self.birthdate, date_format)