[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>

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

addons/web/static/src/js/views/list/list_controller.js

@@ -410,7 +410,7 @@ var ListController = BasicController.extend({
             if (validRecordIds.length > 0) {
                 const dialogOptions = {
                     confirm_callback: () => {
-                        this.model.saveRecords(recordId, validRecordIds, fieldName)
+                        this.model.saveRecords(this.handle, recordId, validRecordIds, fieldName)
                             .then(async () => {
                                 this._updateButtons('readonly');
                                 const state = this.model.get(this.handle);

addons/web/static/src/js/views/list/list_model.js

@@ -37,15 +37,16 @@ odoo.define('web.ListModel', function (require) {
          * For a list of records, performs a write with all changes and fetches
          * all data.
          *
+         * @param {string} listDatapointId id of the parent list
          * @param {string} referenceRecordId the record datapoint used to
          *  generate the changes to apply to recordIds
          * @param {string[]} recordIds a list of record datapoint ids
          * @param {string} fieldName the field to write
          */
-        saveRecords: function (referenceRecordId, recordIds, fieldName) {
+        saveRecords: function (listDatapointId, referenceRecordId, recordIds, fieldName) {
             var self = this;
             var referenceRecord = this.localData[referenceRecordId];
-            var list = this.localData[referenceRecord.parentID];
+            var list = this.localData[listDatapointId];
             // generate all record values to ensure that we'll write something
             // (e.g. 2 records selected, edit a many2one in the first one, but
             // reset same value, we still want to save this value on the other

addons/web/static/tests/views/list_tests.js

@@ -6042,6 +6042,38 @@ QUnit.module('Views', {
         list.destroy();
     });
 
+    QUnit.test('editable list view: m2m tags in grouped list', async function (assert) {
+        assert.expect(2);
+
+        const list = await createView({
+            arch: `
+                <tree editable="top" multi_edit="1">
+                    <field name="bar"/>
+                    <field name="m2m" widget="many2many_tags"/>
+                </tree>`,
+            data: this.data,
+            groupBy: ['bar'],
+            model: 'foo',
+            View: ListView,
+        });
+
+        // Opens first group
+        await testUtils.dom.click(list.$('.o_group_header:first'));
+
+        assert.notEqual(list.$('.o_data_row:first').text(), list.$('.o_data_row:last').text(),
+            "First row and last row should have different values");
+
+        await testUtils.dom.click(list.$('thead .o_list_record_selector:first input'));
+        await testUtils.dom.click(list.$('.o_data_row:first .o_data_cell:eq(1)'));
+        await testUtils.dom.click(list.$('.o_selected_row .o_field_many2manytags .o_delete:first'));
+        await testUtils.dom.click($('.modal .btn-primary'));
+
+        assert.strictEqual(list.$('.o_data_row:first').text(), list.$('.o_data_row:last').text(),
+            "All rows should have been correctly updated");
+
+        list.destroy();
+    });
+
     QUnit.test('list grouped by date:month', async function (assert) {
         assert.expect(1);