[FIX] web: update column in grouped kanban

In a kanban grouped by many2one with a progressbar, after emptying a column
by moving all records, the column wasn't correctly updated. This was causing,
in the best case, a record duplication or, in the worst case, a traceback.

This issue comes from the fact that, with a progressbar, a read_group is
performed each time a record is moved. When the group (column) becomes empty,
the read_group won't return this group even though the group still appears in
the kankan. When moving back the record in this empty column, there is a
desynchronization between the kanban controller data and the model.

To fix this issue, an option `keepEmptyGroups` is passed when performing the
mentioned read_group ; this mimics the kanban display that keeps empty groups
displayed and there is no desync anymore.

Fixes #23982

addons/web/static/src/js/views/basic/basic_model.js

@@ -3166,6 +3166,9 @@ var BasicModel = AbstractModel.extend({
      * @param {Object} [options]
      * @param {string[]} [options.fieldNames] the fields to fetch for a record
      * @param {boolean} [options.onlyGroups=false]
+     * @param {boolean} [options.keepEmptyGroups=false] if set, the groups not
+     *   present in the read_group anymore (empty groups) will stay in the
+     *   datapoint (used to mimic the kanban renderer behaviour for example)
      * @returns {Deferred}
      */
     _load: function (dataPoint, options) {
@@ -3796,6 +3799,16 @@ var BasicModel = AbstractModel.extend({
                         defs.push(self._load(newGroup, options));
                     }
                 });
+                if (options && options.keepEmptyGroups) {
+                    // Find the groups that were available in a previous
+                    // readGroup but are not there anymore.
+                    // Note that these groups are put after existing groups so
+                    // the order is not conserved. A sort *might* be useful.
+                    var emptyGroupsIDs = _.difference(_.pluck(previousGroups, 'id'), list.data);
+                    _.each(emptyGroupsIDs, function (groupID) {
+                        list.data.push(groupID);
+                    });
+                }
                 return $.when.apply($, defs).then(function () {
                     // generate the res_ids of the main list, being the concatenation
                     // of the fetched res_ids in each group

addons/web/static/src/js/views/kanban/kanban_model.js

@@ -369,7 +369,10 @@ var KanbanModel = BasicModel.extend({
         while (element) {
             if (element.progressBar) {
                 return def.then(function (data) {
-                    return self._load(element, {onlyGroups: true}).then(function () {
+                    return self._load(element, {
+                        keepEmptyGroups: true,
+                        onlyGroups: true,
+                    }).then(function () {
                         return data;
                     });
                 });

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

@@ -2544,6 +2544,51 @@ QUnit.module('Views', {
         kanban.destroy();
     });
 
+    QUnit.test('drag & drop records grouped by m2o with progressbar', function (assert) {
+        assert.expect(4);
+
+        this.data.partner.records[0].product_id = false;
+
+        var kanban = createView({
+            View: KanbanView,
+            model: 'partner',
+            data: this.data,
+            arch:
+                '<kanban>' +
+                    '<progressbar field="foo" colors=\'{"yop": "success", "gnap": "warning", "blip": "danger"}\'/>' +
+                    '<templates><t t-name="kanban-box">' +
+                        '<div>' +
+                            '<field name="int_field"/>' +
+                        '</div>' +
+                    '</t></templates>' +
+                '</kanban>',
+            groupBy: ['product_id'],
+            mockRPC: function (route, args) {
+                if (route === '/web/dataset/resequence') {
+                    return $.when(true);
+                }
+                return this._super(route, args);
+            },
+        });
+
+        assert.strictEqual(kanban.$('.o_kanban_group:eq(0) .o_kanban_counter_side').text(), "1",
+            "counter should contain the correct value");
+
+        testUtils.dragAndDrop(kanban.$('.o_kanban_group:eq(0) .o_kanban_record:eq(0)'), kanban.$('.o_kanban_group:eq(1)'));
+        assert.strictEqual(kanban.$('.o_kanban_group:eq(0) .o_kanban_counter_side').text(), "0",
+            "counter should contain the correct value");
+
+        testUtils.dragAndDrop(kanban.$('.o_kanban_group:eq(1) .o_kanban_record:eq(2)'), kanban.$('.o_kanban_group:eq(0)'));
+        assert.strictEqual(kanban.$('.o_kanban_group:eq(0) .o_kanban_counter_side').text(), "1",
+            "counter should contain the correct value");
+
+        testUtils.dragAndDrop(kanban.$('.o_kanban_group:eq(0) .o_kanban_record:eq(0)'), kanban.$('.o_kanban_group:eq(1)'));
+        assert.strictEqual(kanban.$('.o_kanban_group:eq(0) .o_kanban_counter_side').text(), "0",
+            "counter should contain the correct value");
+
+        kanban.destroy();
+    });
+
     QUnit.test('keep adding quickcreate in first column after a record from this column was moved', function (assert) {
         assert.expect(2);