From dc9e69be9091a898756dbb2fac7bae1daebd75ad Mon Sep 17 00:00:00 2001
From: Andreas Opferkuch <andreas.opferkuch@gmail.com>
Date: Tue, 5 May 2020 17:34:49 +0200
Subject: [PATCH] Prometheus: Show "Loading metrics..." when switching sources
 (#24292)

syntaxLoaded needed resetting at the beginning of refreshing
metrics.

Fixes #24291

(cherry picked from commit dfe2ab9502e0ad4a0288a075f2980cd3be00f4e9)
---
 .../datasource/prometheus/components/PromQueryField.tsx       | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/public/app/plugins/datasource/prometheus/components/PromQueryField.tsx b/public/app/plugins/datasource/prometheus/components/PromQueryField.tsx
index 01d2f4404e6..ddc96f21015 100644
--- a/public/app/plugins/datasource/prometheus/components/PromQueryField.tsx
+++ b/public/app/plugins/datasource/prometheus/components/PromQueryField.tsx
@@ -187,6 +187,10 @@ class PromQueryField extends React.PureComponent<PromQueryFieldProps, PromQueryF
       datasource: { languageProvider },
     } = this.props;
 
+    this.setState({
+      syntaxLoaded: false,
+    });
+
     Prism.languages[PRISM_SYNTAX] = languageProvider.syntax;
     this.languageProviderInitializationPromise = makePromiseCancelable(languageProvider.start());
     this.languageProviderInitializationPromise.promise