[FIX] web: grouped list multi edit with m2m

Before this commit, m2m fields were not updated when multi editing
in a grouped list.

Now, the fields are updated no matter how many levels of groupBys
are applied to the list.

Part of task 2078807

closes odoo/odoo#37589

Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>

1 files changed, 9 insertions, 1 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 ce8d028d0af..d4e966440cb 100644
--- a/addons/web/static/src/js/views/basic/basic_model.js
+++ b/addons/web/static/src/js/views/basic/basic_model.js
@@ -3356,7 +3356,15 @@ var BasicModel = AbstractModel.extend({
         var viewType = view ? view.type : fieldInfo.viewType;
 
         var toFetch = {};
-        _.each(list.data, function (dataPoint) {
+
+        // flattens the list.data ids in a grouped case
+        let dataPointIds = list.data;
+        for (let i = 0; i < list.groupedBy.length; i++) {
+            dataPointIds = dataPointIds.reduce((acc, groupId) =>
+                acc.concat(this.localData[groupId].data), []);
+        }
+
+        dataPointIds.forEach(function (dataPoint) {
             var record = self.localData[dataPoint];
             if (typeof record.data[fieldName] === 'string'){
                 // in this case, the value is a local ID, which means that the