[FIX] base: fix validation for co-model field in ir_field view

The co-model field in `IrField` view is accepting Related Model name
even if it is invalid. And replaces the invalid model name with `_unknown`.
This causes KeyError `display_name` when trying to create or read a record.

To fix that we are adding Validations for the Related Model field when it gets
updated from UI side.

sentry-3933471439

closes odoo/odoo#118052

X-original-commit: e4f7798fd5a5cccd5d385f535fbc21264cb6948b
Signed-off-by: Rémy Voet <ryv@odoo.com>

odoo/addons/base/i18n/base.pot

@@ -22402,6 +22402,13 @@ msgstr ""
 msgid "Unknown field name '%s' in related field '%s'"
 msgstr ""
 
+#. module: base
+#. odoo-python
+#: code:addons/base/models/ir_model.py:0
+#, python-format
+msgid "Unknown model name '%s' in Related Model"
+msgstr ""
+
 #. module: base
 #. odoo-python
 #: code:addons/base/models/ir_fields.py:0

odoo/addons/base/models/ir_model.py

@@ -638,6 +638,19 @@ class IrModelFields(models.Model):
             self.relation = field.relation
             self.readonly = True
 
+    @api.onchange('relation')
+    def _onchange_relation(self):
+        try:
+            self._check_relation()
+        except ValidationError as e:
+            return {'warning': {'title': _("Model %s does not exist", self.relation), 'message': e}}
+
+    @api.constrains('relation')
+    def _check_relation(self):
+        for rec in self:
+            if rec.state == 'manual' and rec.relation and not rec.env['ir.model']._get_id(rec.relation):
+                raise ValidationError(_("Unknown model name '%s' in Related Model", rec.relation))
+
     @api.constrains('depends')
     def _check_depends(self):
         """ Check whether all fields in dependencies are valid. """
@@ -684,12 +697,7 @@ class IrModelFields(models.Model):
     def _onchange_ttype(self):
         if self.ttype == 'many2many' and self.model_id and self.relation:
             if self.relation not in self.env:
-                return {
-                    'warning': {
-                        'title': _('Model %s does not exist', self.relation),
-                        'message': _('Please specify a valid model for the object relation'),
-                    }
-                }
+                return
             names = self._custom_many2many_names(self.model_id.model, self.relation)
             self.relation_table, self.column1, self.column2 = names
         else:

odoo/addons/base/tests/test_ir_actions.py

@@ -563,6 +563,21 @@ class TestCustomFields(common.TransactionCase):
         for partner in partners:
             self.assertEqual(partner.x_oh_boy, partner.country_id.code)
 
+    def test_relation_of_a_custom_field(self):
+        """ change the relation model of a custom field """
+        model = self.env['ir.model'].search([('model', '=', self.MODEL)])
+        field = self.env['ir.model.fields'].create({
+            'name': 'x_foo',
+            'model_id': model.id,
+            'field_description': 'x_foo',
+            'ttype': 'many2many',
+            'relation': self.COMODEL,
+        })
+
+        # change the relation
+        with self.assertRaises(ValidationError):
+            field.relation = 'foo'
+
     def test_selection(self):
         """ custom selection field """
         Model = self.env[self.MODEL]