[FIX] models: make inverse of x2many fields work

odoo/addons/test_inherits/ir.model.access.csv

@@ -1,5 +1,6 @@
 "id","name","model_id:id","group_id:id","perm_read","perm_write","perm_create","perm_unlink"
 access_test_unit,access_test_unit,model_test_unit,,1,1,1,1
+access_test_unit_line,access_test_unit_line,model_test_unit_line,,1,1,1,1
 access_test_box,access_test_box,model_test_box,,1,1,1,1
 access_test_pallet,access_test_pallet,model_test_pallet,,1,1,1,1
 access_test_another_unit,access_test_another_unit,model_test_another_unit,,1,1,1,1

odoo/addons/test_inherits/models.py

@@ -11,6 +11,7 @@ class Unit(models.Model):
     name = fields.Char('Name', required=True)
     state = fields.Selection([('a', 'A'), ('b', 'B')], string='State')
     surname = fields.Char(compute='_compute_surname')
+    line_ids = fields.One2many('test.unit.line', 'unit_id')
 
     @api.depends('name')
     def _compute_surname(self):
@@ -18,6 +19,14 @@ class Unit(models.Model):
             unit.surname = unit.name or ''
 
 
+class UnitLine(models.Model):
+    _name = 'test.unit.line'
+    _description = 'Test Unit Line'
+
+    name = fields.Char('Name', required=True)
+    unit_id = fields.Many2one('test.unit', required=True)
+
+
 # We want to _inherits from the parent model and we add some fields
 # in the child object
 class Box(models.Model):

odoo/addons/test_inherits/tests/test_inherits.py

@@ -28,6 +28,26 @@ class test_inherits(common.TransactionCase):
         pallet.write({'name': 'C'})
         self.assertEqual(pallet.name, 'C')
 
+    def test_write_4_one2many(self):
+        """ Check that we can write on an inherited one2many field. """
+        box = self.env.ref('test_inherits.box_a')
+        box.write({'line_ids': [(0, 0, {'name': 'Line 1'})]})
+        self.assertTrue(all(box.line_ids._ids))
+        self.assertEqual(box.line_ids.mapped('name'), ['Line 1'])
+        self.assertEqual(box.line_ids, box.unit_id.line_ids)
+        box.flush()
+        box.invalidate_cache(['line_ids'])
+        box.write({'line_ids': [(0, 0, {'name': 'Line 2'})]})
+        self.assertTrue(all(box.line_ids._ids))
+        self.assertEqual(box.line_ids.mapped('name'), ['Line 1', 'Line 2'])
+        self.assertEqual(box.line_ids, box.unit_id.line_ids)
+        box.flush()
+        box.invalidate_cache(['line_ids'])
+        box.write({'line_ids': [(1, box.line_ids[0].id, {'name': 'First line'})]})
+        self.assertTrue(all(box.line_ids._ids))
+        self.assertEqual(box.line_ids.mapped('name'), ['First line', 'Line 2'])
+        self.assertEqual(box.line_ids, box.unit_id.line_ids)
+
     def test_ir_model_data_inherits(self):
         """ Check the existence of the correct ir.model.data """
         IrModelData = self.env['ir.model.data']

odoo/models.py

@@ -3396,6 +3396,14 @@ Record ids: %(records)s
         for fname in vals:
             field = self._fields[fname]
             if field.inverse:
+                if field.type in ('one2many', 'many2many'):
+                    # The written value is a list of commands that must applied
+                    # on the field's current value. Because the field is
+                    # protected while being written, the field's current value
+                    # will not be computed and default to an empty recordset. So
+                    # make sure the field's value is in cache before writing, in
+                    # order to avoid an inconsistent update.
+                    self[fname]
                 determine_inverses[field.inverse].append(field)
                 # DLE P150: `test_cancel_propagation`, `test_manufacturing_3_steps`, `test_manufacturing_flow`
                 # TODO: check whether still necessary
@@ -3403,7 +3411,17 @@ Record ids: %(records)s
             if field.relational or self._field_inverses[field]:
                 relational_names.append(fname)
             if field.compute and not field.readonly:
-                protected.update(self._field_computed.get(field, [field]))
+                if field.store or field.type not in ('one2many', 'many2many'):
+                    # Protect the field from being recomputed while being
+                    # inversed. In the case of non-stored x2many fields, the
+                    # field's value may contain unexpeced new records (created
+                    # by command 0). Those new records are necessary for
+                    # inversing the field, but should no longer appear if the
+                    # field is recomputed afterwards. Not protecting the field
+                    # will automatically invalidate the field from the cache,
+                    # forcing its value to be recomputed once dependencies are
+                    # up-to-date.
+                    protected.update(self._field_computed.get(field, [field]))
             if fname == 'company_id' or (field.relational and field.check_company):
                 check_company = True