[FIX] web: keep col group by on 2nd reload+after 0 result

In 11.0 f8b38f64d improved the column group by managment when reloading
several times by having the same "groupbys" dictionaries between the
pivot model instance and the header menu.

This has been reverted in 12.0 (with c6e7adfb95d) because the following
pivot tests failed with the change:
- 'rendering of pivot view with comparison'
- 'export data in excel with comparison'

The failure is because now that the "groupbys" dictionaries are the same
object, the truncated dictionary of a header truncate the one of the
model instance.

So if we search something that has no results, then something with
results, the groupbys could be lost.

This behavior has no reason to be and is changed in 11.0 with #31644,
this commit is the forward-port of f8b38f64d and #31644.

closes #31627

Signed-off-by: Nicolas Lempereur (nle) <nle@odoo.com>

1 files changed, 2 insertions, 16 deletions

diff --git a/addons/web/static/src/js/views/pivot/pivot_model.js b/addons/web/static/src/js/views/pivot/pivot_model.js
index 88d0aee83b8..5758b906421 100644
--- a/addons/web/static/src/js/views/pivot/pivot_model.js
+++ b/addons/web/static/src/js/views/pivot/pivot_model.js
@@ -440,12 +440,10 @@ var PivotModel = AbstractModel.extend({
                 // if we don't have the key 'groupBy' in params.  In that case,
                 // we want to have the full open state for the groupbys.
                 self._updateTree(old_row.root, self.data.main_row.root);
-                self._updateMainGroupBys(old_row, self.data.main_row);
             }
 
             if (!('pivot_column_groupby' in (params.context || {}))) {
                 self._updateTree(old_col.root, self.data.main_col.root);
-                self._updateMainGroupBys(old_col, self.data.main_col);
             }
         });
     },
@@ -986,7 +984,8 @@ var PivotModel = AbstractModel.extend({
         });
 
         var index = 0;
-        var rowGroupBys = !_.isEmpty(this.data.groupedBy) ? this.data.groupedBy : this.initialRowGroupBys;
+        var rowGroupBys = !_.isEmpty(this.data.groupedBy) ? this.data.groupedBy : this.initialRowGroupBys.slice();
+        this.data.groupedBy = rowGroupBys;
         var colGroupBys = this.data.colGroupBys;
         var dataPoint, row, col, attrs, cell_value;
         var main_row_header, main_col_header;
@@ -1119,19 +1118,6 @@ var PivotModel = AbstractModel.extend({
         }
     },
     /**
-     * Updates the groupBys that the main[row | col] holds
-     *
-     * @private
-     * @param {Object} old: The main abstract header before reload
-     * @param {Object} main: The main abstract header after reload
-     *
-     */
-    _updateMainGroupBys: function (old, main) {
-        var new_groupby_length = this._getHeaderDepth(main.root) - 1;
-        var new_groupby_list = old.root.groupbys.slice(0, new_groupby_length);
-        main.root.groupbys = new_groupby_list;
-    },
-    /**
      * @param {Object} old_tree
      * @param {Object} new_tree
      */