From 7c8184d5bfa05867f7d25305053259f271da56f9 Mon Sep 17 00:00:00 2001
From: Sergej-Vlasov <37613182+Sergej-Vlasov@users.noreply.github.com>
Date: Tue, 20 Aug 2024 11:55:04 +0300
Subject: [PATCH] DashboardModel - Add fallback for variable current value
 fallback (#91833)

* add variable current value fallback when null

* refactor to avoid loosing reference
---
 .../dashboard/state/DashboardModel.ts         | 26 +++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/public/app/features/dashboard/state/DashboardModel.ts b/public/app/features/dashboard/state/DashboardModel.ts
index fce70c7f03d..057d621d706 100644
--- a/public/app/features/dashboard/state/DashboardModel.ts
+++ b/public/app/features/dashboard/state/DashboardModel.ts
@@ -19,7 +19,7 @@ import {
 } from '@grafana/data';
 import { PromQuery } from '@grafana/prometheus';
 import { RefreshEvent, TimeRangeUpdatedEvent, config } from '@grafana/runtime';
-import { Dashboard, DashboardLink } from '@grafana/schema';
+import { Dashboard, DashboardLink, VariableModel } from '@grafana/schema';
 import { DEFAULT_ANNOTATION_COLOR } from '@grafana/ui';
 import { GRID_CELL_HEIGHT, GRID_CELL_VMARGIN, GRID_COLUMN_COUNT, REPEAT_DIR_VERTICAL } from 'app/core/constants';
 import { contextSrv } from 'app/core/services/context_srv';
@@ -145,7 +145,7 @@ export class DashboardModel implements TimeModel {
     this.time = data.time ?? { from: 'now-6h', to: 'now' };
     this.timepicker = data.timepicker ?? {};
     this.liveNow = data.liveNow;
-    this.templating = this.ensureListExist(data.templating);
+    this.templating = this.removeNullValuesFromVariables(this.ensureListExist(data.templating));
     this.annotations = this.ensureListExist(data.annotations);
     this.refresh = data.refresh;
     this.snapshot = data.snapshot;
@@ -471,6 +471,28 @@ export class DashboardModel implements TimeModel {
     }
   }
 
+  private removeNullValuesFromVariables(templating: { list: VariableModel[] }) {
+    if (!templating.list.length) {
+      return templating;
+    }
+
+    for (const variable of templating.list) {
+      if (variable.current) {
+        // this is a safeguard for null value that breaks scenes dashboards.
+        //    expecting error at .includes(null) in order to not adjust
+        //    VariableOption type to avoid breaking changes
+        if (
+          variable.current.value === null ||
+          //@ts-expect-error
+          (Array.isArray(variable.current.value) && variable.current.value.includes(null))
+        ) {
+          variable.current = undefined;
+        }
+      }
+    }
+    return templating;
+  }
+
   private ensureListExist(data: any = {}) {
     data.list ??= [];
     return data;