[FIX] core: import of o2m with recursive xml declaration

Let's imagine this data

```xml
<record model="my.model" id="1">
    <field name="name">parent</field>
    <field name="children_ids">
	<record model="my.model" id="1.1">
	    <field name="name">child</field>
	</record>
    </field>
</record>
```

Loading this data the first time, everything works fine.
But if we update it, this is what happens:
* load `my.model,1`: write on `name=parent` and `children_ids=None`
* load `my.model,1.1`: write on `name=child` and `parent_id=my.model,1`

The write on `children_ids=None` can unlink all the children if the
field is declared as `ondelete=cascade`
That will leade in all the records to be deleted and recreated, but
without keeping links with other documents.

For instance, when upgrading the `account` module, all the
`account.account.tag` are removed from `account.move.line` because when
the `account.tax.report.line` are updated, all the tags are deleted and
recreated.

closes odoo/odoo#82793

X-original-commit: de00316fa42173f3a5c394458bb4418e59e298cd
Signed-off-by: Raphael Collet <rco@odoo.com>
Signed-off-by: William André (wan) <wan@odoo.com>
Co-authored-by: rco-odoo <rco@odoo.com>
Co-authored-by: jva-odoo <jva@odoo.com>
Co-authored-by: william-andre <wan@odoo.com>

odoo/addons/test_convert/models.py

@@ -7,6 +7,8 @@ class TestModel(models.Model):
     _name = 'test_convert.test_model'
     _description = "Test Convert Model"
 
+    usered_ids = fields.One2many('test_convert.usered', 'test_id')
+
     @api.model
     def action_test_date(self, today_date):
         return True
@@ -25,6 +27,7 @@ class Usered(models.Model):
 
     name = fields.Char()
     user_id = fields.Many2one('res.users', default=lambda self: self.env.user)
+    test_id = fields.Many2one('test_convert.test_model')
     tz = fields.Char(default=lambda self: self.env.context.get('tz') or self.env.user.tz)
 
     @api.model

odoo/addons/test_convert/tests/test_convert.py

@@ -188,6 +188,37 @@ class TestEvalXML(common.TransactionCase):
         self.assertEqual(args, ())
         self.assertEqual(kwargs, {})
 
+    def test_o2m_sub_records(self):
+        # patch the model's class with a proxy that copies the argument
+        Model = self.registry['test_convert.test_model']
+        call_args = []
+
+        def _load_records(self, data_list, update=False):
+            call_args.append(data_list)
+            # pylint: disable=bad-super-call
+            return super(Model, self)._load_records(data_list, update=update)
+
+        self.patch(Model, '_load_records', _load_records)
+
+        # import a record with a subrecord
+        xml = ET.fromstring("""
+            <record id="test_convert.test_o2m_record" model="test_convert.test_model">
+                <field name="usered_ids">
+                    <record id="test_convert.test_o2m_subrecord" model="test_convert.usered">
+                        <field name="name">subrecord</field>
+                    </record>
+                </field>
+            </record>
+        """.strip())
+        obj = xml_import(self.cr, 'test_convert', None, 'init')
+        obj._tag_record(xml)
+
+        # check that field 'usered_ids' is not passed
+        self.assertEqual(len(call_args), 1)
+        for data in call_args[0]:
+            self.assertNotIn('usered_ids', data['values'],
+                             "Unexpected value in O2M When loading XML with sub records")
+
     @unittest.skip("not tested")
     def test_xml(self):
         pass

odoo/tools/convert.py

@@ -579,10 +579,12 @@ form: module.record_id""" % (xml_id,)
                     elif field_type == 'boolean' and isinstance(f_val, str):
                         f_val = str2bool(f_val)
                     elif field_type == 'one2many':
-                        if isinstance(f_val, str):
-                            f_val = None
                         for child in field.findall('./record'):
                             sub_records.append((child, model._fields[f_name].inverse_name))
+                        if isinstance(f_val, str):
+                            # We do not want to write on the field since we will write
+                            # on the childrens' parents later
+                            continue
             res[f_name] = f_val
         if extra_vals:
             res.update(extra_vals)