From 689230161cdc2a538f73aa8470f500f861945bbc Mon Sep 17 00:00:00 2001
From: Mostafa Moradian <mostafa@grafana.com>
Date: Mon, 24 Feb 2025 10:27:33 +0100
Subject: [PATCH] Stay backward compatible

---
 pkg/services/ngalert/state/historian/loki_http.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pkg/services/ngalert/state/historian/loki_http.go b/pkg/services/ngalert/state/historian/loki_http.go
index 5d84998a84a..3720d7c7744 100644
--- a/pkg/services/ngalert/state/historian/loki_http.go
+++ b/pkg/services/ngalert/state/historian/loki_http.go
@@ -159,6 +159,12 @@ type Sample struct {
 }
 
 func (r *Sample) MarshalJSON() ([]byte, error) {
+	// For backward compatibility, if M is nil, we don't include it in the JSON.
+	if r.M == nil {
+		return json.Marshal([]any{
+			fmt.Sprintf("%d", r.T.UnixNano()), r.V,
+		})
+	}
 	return json.Marshal([]any{
 		fmt.Sprintf("%d", r.T.UnixNano()), r.V, r.M,
 	})