feat(alerting): shows when no_data triggered alerts

closes #7035
ref #7257

pkg/api/alerting.go

@@ -75,6 +75,7 @@ func GetAlerts(c *middleware.Context) Response {
 			State:          alert.State,
 			NewStateDate:   alert.NewStateDate,
 			ExecutionError: alert.ExecutionError,
+			EvalData:       alert.EvalData,
 		})
 	}
 

pkg/api/dtos/alerting.go

@@ -17,6 +17,7 @@ type AlertRule struct {
 	State          m.AlertStateType `json:"state"`
 	NewStateDate   time.Time        `json:"newStateDate"`
 	EvalDate       time.Time        `json:"evalDate"`
+	EvalData       *simplejson.Json `json:"evalData"`
 	ExecutionError string           `json:"executionError"`
 	DashbboardUri  string           `json:"dashboardUri"`
 }

pkg/services/alerting/result_handler.go

@@ -31,13 +31,17 @@ func (handler *DefaultResultHandler) Handle(evalContext *EvalContext) error {
 	executionError := ""
 	annotationData := simplejson.New()
 
+	if evalContext.Firing {
+		annotationData = simplejson.NewFromAny(evalContext.EvalMatches)
+	}
+
 	if evalContext.Error != nil {
 		executionError = evalContext.Error.Error()
 		annotationData.Set("errorMessage", executionError)
 	}
 
-	if evalContext.Firing {
-		annotationData = simplejson.NewFromAny(evalContext.EvalMatches)
+	if evalContext.NoDataFound {
+		annotationData.Set("no_data", true)
 	}
 
 	countStateResult(evalContext.Rule.State)

pkg/services/sqlstore/alert.go

@@ -113,6 +113,12 @@ func HandleAlertsQuery(query *m.GetAlertsQuery) error {
 		return err
 	}
 
+	for i, _ := range alerts {
+		if alerts[i].ExecutionError == " " {
+			alerts[i].ExecutionError = ""
+		}
+	}
+
 	query.Result = alerts
 	return nil
 }