Chore: Mark prometheus query json unmarshaling errors as downstream error (#112314)

* mark json unmarshaling errors as downstream

* shortcut

pkg/promlib/models/query.go

@@ -13,11 +13,13 @@ import (
 	"github.com/grafana/grafana-plugin-sdk-go/backend"
 	"github.com/grafana/grafana-plugin-sdk-go/backend/gtime"
 	sdkapi "github.com/grafana/grafana-plugin-sdk-go/experimental/apis/data/v0alpha1"
-	scope "github.com/grafana/grafana/apps/scope/pkg/apis/scope/v0alpha1"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
 
+	scope "github.com/grafana/grafana/apps/scope/pkg/apis/scope/v0alpha1"
+
 	glog "github.com/grafana/grafana-plugin-sdk-go/backend/log"
+
 	"github.com/grafana/grafana/pkg/promlib/intervalv2"
 )
 
@@ -164,7 +166,7 @@ type internalQueryModel struct {
 func Parse(ctx context.Context, log glog.Logger, span trace.Span, query backend.DataQuery, dsScrapeInterval string, intervalCalculator intervalv2.Calculator, fromAlert bool) (*Query, error) {
 	model := &internalQueryModel{}
 	if err := json.Unmarshal(query.JSON, model); err != nil {
-		return nil, err
+		return nil, backend.DownstreamErrorf("error unmarshaling query: %w", err)
 	}
 	span.SetAttributes(attribute.String("rawExpr", model.Expr))
 

pkg/promlib/models/query_test.go

@@ -1307,6 +1307,40 @@ func TestParseComplexScenariosWithFilters(t *testing.T) {
 	})
 }
 
+func TestParseNumericFormatError(t *testing.T) {
+	_, span := tracer.Start(context.Background(), "operation")
+	defer span.End()
+
+	timeRange := backend.TimeRange{
+		From: now,
+		To:   now.Add(12 * time.Hour),
+	}
+
+	// Test case where format is sent as a number instead of string
+	queryJson := `{
+		"expr": "up",
+		"format": 0,
+		"refId": "A"
+	}`
+
+	q := backend.DataQuery{
+		JSON:      []byte(queryJson),
+		TimeRange: timeRange,
+		RefID:     "A",
+	}
+
+	res, err := models.Parse(context.Background(), log.New(), span, q, "15s", intervalCalculator, false)
+
+	require.Error(t, err)
+	require.Nil(t, res)
+
+	require.True(t, backend.IsDownstreamError(err))
+
+	// Error message should indicate unmarshaling issue
+	require.Contains(t, err.Error(), "error unmarshaling query")
+	require.Contains(t, err.Error(), "cannot unmarshal number")
+}
+
 func TestQueryTypeDefinitions(t *testing.T) {
 	builder, err := schemabuilder.NewSchemaBuilder(
 		schemabuilder.BuilderOptions{