[FIX] In new records *2many, enable to handle multiple RPC inputs

closes odoo/odoo#24458

Signed-off-by: Raphael Collet (rco) <rco@openerp.com>

odoo/addons/test_new_api/tests/test_one2many.py

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-from openerp.tests.common import TransactionCase
+from odoo.tests.common import TransactionCase
 
 
 class One2manyCase(TransactionCase):
@@ -51,6 +51,8 @@ class One2manyCase(TransactionCase):
         self.multi.lines = self.multi.lines[:-1]
         self.assertEqual(len(self.multi.lines), 9)
         self.assertIn("hello", self.multi.lines.mapped('name'))
+        if not self.multi.id:
+            return
         # Invalidate the cache and check again; this crashes if the value
         # of self.multi.lines in cache contains new records
         self.multi.invalidate_cache()
@@ -89,11 +91,26 @@ class One2manyCase(TransactionCase):
             self.multi.lines = [(0, 0, {"name": str(name)})]
         self.operations()
 
+    def test_rpcstyle_one_by_one_on_new(self):
+        self.multi = self.env["test_new_api.multi"].new({
+            "name": "What is up?"
+        })
+        for name in range(10):
+            self.multi.lines = [(0, 0, {"name": str(name)})]
+        self.operations()
+
     def test_rpcstyle_single(self):
         """Check lines created with RPC style and added in one step"""
         self.multi.lines = [(0, 0, {'name': str(name)}) for name in range(10)]
         self.operations()
 
+    def test_rpcstyle_single_on_new(self):
+        self.multi = self.env["test_new_api.multi"].new({
+            "name": "What is up?"
+        })
+        self.multi.lines = [(0, 0, {'name': str(name)}) for name in range(10)]
+        self.operations()
+
     def test_many2one_integer(self):
         """Test several models one2many with same inverse Integer field"""
         # utility function to convert records to tuples with id,name

odoo/fields.py

@@ -2080,8 +2080,8 @@ class _RelationalMulti(_Relational):
         elif isinstance(value, (list, tuple)):
             # value is a list/tuple of commands, dicts or record ids
             comodel = record.env[self.comodel_name]
-            # determine the value ids; by convention empty on new records
-            ids = OrderedSet(record[self.name].ids if record.id else ())
+            # determine the value ids
+            ids = OrderedSet(record[self.name]._ids)
             # modify ids with the commands
             for command in value:
                 if isinstance(command, (tuple, list)):