partner-contact/partner_contact_lang/models/res_partner.py

# Copyright 2016 Tecnativa - Pedro M. Baeza <pedro.baeza@tecnativa.com>
# Copyright 2017 Tecnativa - Vicent Cubells <vicent.cubells@tecnativa.com>
# License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl.html).

from odoo import api, fields, models


class ResPartner(models.Model):
    _inherit = "res.partner"

    # HACK https://github.com/odoo/odoo/issues/53738
    # TODO Remove when fixed
    partner_lang = fields.Selection(
        string="Partner lang",
        related="lang",
        readonly=True,
    )

    def write(self, vals):
        """Propagate a language change in the partner to the child contacts."""
        res = super(ResPartner, self).write(vals)
        if vals.get("lang"):
            childs = self.search([("id", "child_of", self.ids), ("lang", "=", False)])
            if childs:
                childs.write({"lang": vals["lang"]})
        return res

    @api.onchange("parent_id")
    def onchange_parent_id(self):
        """Change language if the parent company changes and there's no
        language defined yet"""
        res = super(ResPartner, self).onchange_parent_id()
        if (
            self.parent_id
            and self.parent_id != self
            and not self.lang
            and self.parent_id.lang
        ):
            self.lang = self.parent_id.lang
        return res