logs: use explicit frame-type-check (#48940)

pkg/tsdb/loki/frame.go

@@ -114,7 +114,11 @@ func adjustLogsFrame(frame *data.Frame, query *lokiQuery) error {
 	}
 
 	frame.Meta.Stats = parseStats(frame.Meta.Custom)
-	frame.Meta.Custom = nil
+	// TODO: when we get a real frame-type in grafana-plugin-sdk-go,
+	// move this to frame.Meta.FrameType
+	frame.Meta.Custom = map[string]string{
+		"frameType": "LabeledTimeValues",
+	}
 
 	frame.Meta.ExecutedQueryString = "Expr: " + query.Expr
 

public/app/core/logs_model.test.ts

@@ -387,6 +387,9 @@ describe('dataFrameToLogsModel', () => {
         ],
         meta: {
           limit: 1000,
+          custom: {
+            frameType: 'LabeledTimeValues',
+          },
         },
       }),
     ];
@@ -464,15 +467,24 @@ describe('dataFrameToLogsModel', () => {
       values: ['line1'],
     };
 
+    const meta = {
+      custom: {
+        frameType: 'LabeledTimeValues',
+      },
+    };
+
     const frame1 = new MutableDataFrame({
+      meta,
       fields: [labels, time, line],
     });
 
     const frame2 = new MutableDataFrame({
+      meta,
       fields: [time, labels, line],
     });
 
     const frame3 = new MutableDataFrame({
+      meta,
       fields: [time, line, labels],
     });
 

public/app/core/logs_model.ts

@@ -316,11 +316,11 @@ function getAllLabels(fields: LogFields): Labels[] {
 
   const { stringField, labelsField } = fields;
 
-  const fieldLabels = stringField.labels !== undefined ? [stringField.labels] : [];
-
-  const labelsFieldLabels: Labels[] = labelsField !== undefined ? labelsField.values.toArray() : [];
-
-  return [...fieldLabels, ...labelsFieldLabels];
+  if (labelsField !== undefined) {
+    return labelsField.values.toArray();
+  } else {
+    return [stringField.labels ?? {}];
+  }
 }
 
 function getLabelsForFrameRow(fields: LogFields, index: number): Labels {
@@ -329,10 +329,11 @@ function getLabelsForFrameRow(fields: LogFields, index: number): Labels {
 
   const { stringField, labelsField } = fields;
 
-  return {
-    ...stringField.labels,
-    ...labelsField?.values.get(index),
-  };
+  if (labelsField !== undefined) {
+    return labelsField.values.get(index);
+  } else {
+    return stringField.labels ?? {};
+  }
 }
 
 /**
@@ -357,7 +358,11 @@ export function logSeriesToLogsModel(logSeries: DataFrame[]): LogsModel | undefi
       const fieldCache = new FieldCache(series);
       const stringField = fieldCache.getFirstFieldOfType(FieldType.string);
       const timeField = fieldCache.getFirstFieldOfType(FieldType.time);
-      const labelsField = fieldCache.getFieldByName('labels');
+      // NOTE: this is experimental, please do not use in your code.
+      // we will get this custom-frame-type into the "real" frame-type list soon,
+      // but the name might change, so please do not use it until then.
+      const labelsField =
+        series.meta?.custom?.frameType === 'LabeledTimeValues' ? fieldCache.getFieldByName('labels') : undefined;
 
       if (stringField !== undefined && timeField !== undefined) {
         const info = {

public/app/plugins/datasource/loki/backendResultTransformer.test.ts

@@ -22,6 +22,9 @@ const inputFrame: DataFrame = {
   refId: 'A',
   meta: {
     executedQueryString: LOKI_EXPR,
+    custom: {
+      frameType: 'LabeledTimeValues',
+    },
   },
   fields: [
     {
@@ -71,6 +74,7 @@ describe('loki backendResultTransformer', () => {
       preferredVisualisationType: 'logs',
       searchWords: ['thing1'],
       custom: {
+        ...expectedFrame.meta?.custom,
         lokiQueryStatKey: 'Summary: total bytes processed',
       },
     };

public/app/plugins/datasource/loki/backendResultTransformer.ts

@@ -10,7 +10,7 @@ function isMetricFrame(frame: DataFrame): boolean {
   return frame.fields.every((field) => field.type === FieldType.time || field.type === FieldType.number);
 }
 
-// returns a new frame, with meta merged with it's original meta
+// returns a new frame, with meta shallow merged with it's original meta
 function setFrameMeta(frame: DataFrame, meta: QueryResultMeta): DataFrame {
   const { meta: oldMeta, ...rest } = frame;
   // meta maybe be undefined, we need to handle that
@@ -27,6 +27,7 @@ function processStreamFrame(
   derivedFieldConfigs: DerivedFieldConfig[]
 ): DataFrame {
   const custom: Record<string, string> = {
+    ...frame.meta?.custom, // keep the original meta.custom
     // used by logs_model
     lokiQueryStatKey: 'Summary: total bytes processed',
   };

public/app/plugins/datasource/loki/result_transformer.ts

@@ -334,6 +334,9 @@ export function lokiStreamsToDataFrames(
   // Use custom mechanism to identify which stat we want to promote to label
   const custom = {
     lokiQueryStatKey: 'Summary: total bytes processed',
+    // TODO: when we get a real frame-type in @grafana/data
+    // move this to frame.meta.type
+    frameType: 'LabeledTimeValues',
   };
 
   const meta: QueryResultMeta = {