[FIX] website: fix ctx argument

In the call to Chart.js we pass a ctx which should be a DOM element,
however we pass `null` as the ctx.

It seems that what happens is that we look for the DOM element inside
the `document` (via getElementById) but this element is not yet inserted
into the document, hence this returns `null`.

Since we already have a reference to the canvas element which should be
used as ctx, we can probably just reuse this reference

closes odoo/odoo#36072

Signed-off-by: Adrien Dieudonné (adr) <adr@odoo.com>

2 files changed, 22 insertions, 1 deletions

diff --git a/addons/website/static/src/js/backend/dashboard.js b/addons/website/static/src/js/backend/dashboard.js
index dda40102904..28b9a55c8a4 100644
--- a/addons/website/static/src/js/backend/dashboard.js
+++ b/addons/website/static/src/js/backend/dashboard.js
@@ -185,7 +185,7 @@ var Dashboard = AbstractAction.extend({
             };
         });
 
-        var ctx = document.getElementById(chart_id);
+        var ctx = this.$canvas[0];
         this.chart = new Chart(ctx, {
             type: 'line',
             data: {
diff --git a/addons/website/static/tests/tours/dashboard_tour.js b/addons/website/static/tests/tours/dashboard_tour.js
new file mode 100644
index 00000000000..a8566d63a97
--- /dev/null
+++ b/addons/website/static/tests/tours/dashboard_tour.js
@@ -0,0 +1,21 @@
+odoo.define("website.tour.backend_dashboard", function (require) {
+"use strict";
+
+var tour = require("web_tour.tour");
+
+tour.register("backend_dashboard", {
+    test: true,
+    url: "/web",
+}, [tour.STEPS.SHOW_APPS_MENU_ITEM,
+    {
+    trigger: 'a[data-menu-xmlid="website.menu_website_configuration"]',
+    run: 'click',
+}, {
+    trigger: '.dropdown-toggle[data-menu-xmlid="website.menu_dashboard"]',
+    run: 'click',
+}, {
+    trigger: '.dropdown-item[data-menu-xmlid="website.menu_website_google_analytics"]',
+    content: 'Check if traceback',
+    run: 'click',
+}]);
+});