[FIX] hr_expense,web: explicit link_to command for o2m

The ORM doesn't automatically link subrecords when it receives an
update command for a one2many. However, it may be necessary when
the default_get returns existing records for a one2many field. It
only worked before this rev. for the hr_expense model because of an
hack from 2016 (to reproduce: go to Expenses, check some expenses
from the list view, in Actions, click on 'Submit to Manager', the
new hr_expense_sheet contains the checked expenses (one2many), and
the webclient only sent an update command by linked subrecord).

This rev. fixes the problem properly: when the default_get returns
existing subrecords for a one2many field, a link_to command (4) is
generated alongside the update (1) command.

1 files changed, 10 insertions, 2 deletions

diff --git a/addons/web/static/src/js/views/basic/basic_model.js b/addons/web/static/src/js/views/basic/basic_model.js
index c450e2bedc7..1d8e68c3e62 100644
--- a/addons/web/static/src/js/views/basic/basic_model.js
+++ b/addons/web/static/src/js/views/basic/basic_model.js
@@ -2634,13 +2634,21 @@ var BasicModel = AbstractModel.extend({
                             }
                             commands[fieldName].push(command);
                         } else if (_.contains(addedIds, list.res_ids[i])) {
-                            // this is a new id
+                            // this is a new id (maybe existing in DB, but new in JS)
                             relRecord = _.findWhere(relRecordAdded, {res_id: list.res_ids[i]});
                             changes = this._generateChanges(relRecord, options);
                             if ('id' in changes) {
+                                // the subrecord already exists in db
                                 delete changes.id;
-                                commands[fieldName].push(x2ManyCommands.update(relRecord.res_id, changes));
+                                if (this.isNew(record.id)) {
+                                    // if the main record is new, link the subrecord to it
+                                    commands[fieldName].push(x2ManyCommands.link_to(relRecord.res_id));
+                                }
+                                if (!_.isEmpty(changes)) {
+                                    commands[fieldName].push(x2ManyCommands.update(relRecord.res_id, changes));
+                                }
                             } else {
+                                // the subrecord is new, so create it
                                 commands[fieldName].push(x2ManyCommands.create(changes));
                             }
                         }