Dashboard: replace datasource name with a reference object (#33817)

Co-authored-by: Torkel Ödegaard <torkel@grafana.com>
Co-authored-by: Elfo404 <me@giordanoricci.com>

pkg/expr/graph_test.go

@@ -195,6 +195,33 @@ func TestServicebuildPipeLine(t *testing.T) {
 			},
 			expectErrContains: "classic conditions may not be the input for other expressions",
 		},
+		{
+			name: "Queries with new datasource ref object",
+			req: &Request{
+				Queries: []Query{
+					{
+						RefID: "A",
+						JSON: json.RawMessage(`{
+							"datasource":  {
+										"uid": "MyDS"
+									}
+							}`),
+					},
+					{
+						RefID: "B",
+						JSON: json.RawMessage(`{
+							"datasource":  {
+								"uid": "MyDS"
+							},
+							"expression": "A",
+							"reducer": "mean",
+							"type": "reduce"
+						}`),
+					},
+				},
+			},
+			expectedOrder: []string{"B", "A"},
+		},
 	}
 	s := Service{}
 	for _, tt := range tests {