[FIX] web: make sure m2m_checkbox works twice in a row

We had an interesting bug with the field many2many_checkbox: in some
cases, it could cause a crash, because it could not find an element in the
localdata.

To reproduce this, start with a non empty field many2many checkbox, then
uncheck them twice.

The reason is that the datapoint of type 'list' that represents the
current value is actually modified, and the replace_with operation
assumed that it could find the localID by looking into its data.  I have
the feeling that a more complete fix is to make sure that the datapoint
is not modified (in its 'data' key), but is modified in its '_changes'
key.  However, this would probably be a bigger change.

1 files changed, 3 insertions, 0 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 3591ac3cf94..b4a0b999453 100644
--- a/addons/web/static/src/js/views/basic/basic_model.js
+++ b/addons/web/static/src/js/views/basic/basic_model.js
@@ -1541,6 +1541,9 @@ var BasicModel = AbstractModel.extend({
                     removedDef = this._applyX2ManyChange(record, fieldName, {
                         operation: 'DELETE',
                         ids: _.map(removedIds, function (resID) {
+                            if (resID in list._cache) {
+                                return list._cache[resID];
+                            }
                             return _.findWhere(listData, {res_id: resID}).id;
                         }),
                     });