[FIX] web: pivot race condition load data

When doing several grouping quickly (or if the system is slow) on the
pivot view, we may try to display data that now doesn't corresponds to
the current selected groupBys.

This commit ensures that when we load data of the pivot view, we drop
the previous data loading that are currently being carried out.

Without the fix, the added test failed with:

  TypeError: Cannot read property 'length' of undefined

because the test does:

- select one level of group by
- select two levels of group by
- resolve the first level of group by
- resolve the second level of group by

Without the fix, we would try to display the data for one level of group
by when the pivot view had two levels selected.

With the fix, displaying the first level of group by was discarded once
a second one was being requested.

opw-1825892
closes #24396

addons/web/static/src/js/views/pivot/pivot_model.js

@@ -17,6 +17,7 @@ odoo.define('web.PivotModel', function (require) {
  */
 
 var AbstractModel = require('web.AbstractModel');
+var concurrency = require('web.concurrency');
 var core = require('web.core');
 var session = require('web.session');
 var utils = require('web.utils');
@@ -32,6 +33,7 @@ var PivotModel = AbstractModel.extend({
         this._super.apply(this, arguments);
         this.numbering = {};
         this.data = null;
+        this._loadDataDropPrevious = new concurrency.DropPrevious();
     },
 
     //--------------------------------------------------------------------------
@@ -532,7 +534,7 @@ var PivotModel = AbstractModel.extend({
             }
         }
 
-        return $.when.apply(null, groupBys.map(function (groupBy) {
+        return this._loadDataDropPrevious.add($.when.apply(null, groupBys.map(function (groupBy) {
             return self._rpc({
                     model: self.modelName,
                     method: 'read_group',
@@ -542,7 +544,7 @@ var PivotModel = AbstractModel.extend({
                     groupBy: groupBy,
                     lazy: false,
                 });
-        })).then(function () {
+        }))).then(function () {
             var data = Array.prototype.slice.call(arguments);
             if (data[0][0].__count === 0) {
                 self.data.has_data = false;

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

@@ -1001,4 +1001,37 @@ QUnit.module('Views', {
 
         pivot.destroy();
     });
+
+    QUnit.test('parallel data loading should discard all but the last one', function (assert) {
+        assert.expect(2);
+
+        var def;
+
+        var pivot = createView({
+            View: PivotView,
+            model: "partner",
+            data: this.data,
+            arch: '<pivot>' +
+                      '<field name="foo" type="measure"/>' +
+                  '</pivot>',
+            mockRPC: function (route, args) {
+                var result = this._super.apply(this, arguments);
+                if (args.method === 'read_group') {
+                    return $.when(def).then(_.constant(result));
+                }
+                return result;
+            },
+        });
+
+        def = $.Deferred();
+        pivot.update({groupBy: ['product_id']});
+        pivot.update({groupBy: ['product_id', 'customer']});
+        def.resolve();
+
+        assert.strictEqual(pivot.$('.o_pivot_cell_value').length, 6,
+            "should have 6 cells");
+        assert.strictEqual(pivot.$('tbody tr').length, 6,
+            "should have 6 rows");
+        pivot.destroy();
+    });
 });});