crock-addons/crock_base/models/res_partner.py

from odoo import models, api


class ResPartner(models.Model):
    _inherit = "res.partner"
    _order = "is_company desc, country_id, department_id, display_name, id"

    @api.onchange("state_id")
    def _onchange_state_id(self):
        state = self.state_id
        if state:
            if self.partner_scale in ["dept", "loc"]:
                crck = self.search(
                    [("partner_scale", "=", "reg"), ("state_id", "=", state)], limit=1
                )
                if crck and crck != self.crck_partner_id:
                    main = self.env.ref("base.main_partner")
                    if self.crck_partner_id != main:
                        self.crck_partner_id = main
            elif self.partner_scale == "reg":
                self.crck_partner_id = self

    @api.onchange("department_id")
    def _onchange_department_id(self):
        dept = self.department_id
        if dept and self.partner_scale == "loc":
            cdck = self.search(
                [("partner_scale", "=", "dep"), ("department_id", "=", dept)], limit=1
            )
            if cdck and cdck != self.cdck_partner_id:
                main = self.env.ref("base.main_partner")
                if self.cdck_partner_id != main:
                    self.cdck_partner_id = main
            elif self.partner_scale == "dep":
                self.cdck_partner_id = self