delivery_carrier_partner_account: make default the first account added to a partner

delivery_carrier_partner_account/models/res_partner.py

@@ -1,4 +1,4 @@
-from odoo import models, fields
+from odoo import models, fields, api
 
 
 class Partner(models.Model):
@@ -16,3 +16,20 @@ class Partner(models.Model):
         tracking=1,
         ondelete="restrict",
     )
+
+    def write(self, vals):
+        update_default_carrier = (
+            "carrier_account_ids" in vals and not self.default_carrier_account_id
+        )
+        res = super().write(vals)
+        if update_default_carrier:
+            self.default_carrier_account_id = self.carrier_account_ids[0]
+        return res
+
+    @api.model_create_multi
+    def create(self, vals_list):
+        res = super().create(vals_list)
+        for rec in res:
+            if not rec.default_carrier_account_id and rec.carrier_account_ids:
+                rec.default_carrier_account_id = rec.carrier_account_ids[0]
+        return res

delivery_carrier_partner_account/tests/__init__.py

@@ -2,3 +2,4 @@ from . import test_carrier_account_common
 from . import test_carrier_account_mixin
 from . import test_choose_delivery_carrier
 from . import test_sale_order
+from . import test_res_partner

delivery_carrier_partner_account/tests/test_res_partner.py

@@ -0,0 +1,30 @@
+from odoo.tests import TransactionCase, tagged
+from odoo import Command
+
+
+@tagged("post_install", "-at_install")
+class TestResPartner(TransactionCase):
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+
+    def test_default_carrier_set_on_create(self):
+        partner = self.env["res.partner"].create(
+            {
+                "name": "Test Partner",
+                "carrier_account_ids": [
+                    Command.create(
+                        {
+                            "delivery_carrier_id": self.env.ref(
+                                "delivery.free_delivery_carrier"
+                            ).id,
+                            "account_number": "1234567890",
+                        }
+                    )
+                ],
+            }
+        )
+
+        self.assertEqual(
+            partner.carrier_account_ids[0], partner.default_carrier_account_id
+        )