grafana/public/app/plugins/datasource/loki/responseUtils.ts

import { DataFrame, FieldType, getParser, Labels, LogsParsers } from '@grafana/data';

export function dataFrameHasLokiError(frame: DataFrame): boolean {
  const labelSets: Labels[] = frame.fields.find((f) => f.name === 'labels')?.values.toArray() ?? [];
  return labelSets.some((labels) => labels.__error__ !== undefined);
}
export function extractLogParserFromDataFrame(frame: DataFrame): { hasLogfmt: boolean; hasJSON: boolean } {
  const lineField = frame.fields.find((field) => field.type === FieldType.string);
  if (lineField == null) {
    return { hasJSON: false, hasLogfmt: false };
  }

  const logLines: string[] = lineField.values.toArray();

  let hasJSON = false;
  let hasLogfmt = false;

  logLines.forEach((line) => {
    const parser = getParser(line);
    if (parser === LogsParsers.JSON) {
      hasJSON = true;
    }
    if (parser === LogsParsers.logfmt) {
      hasLogfmt = true;
    }
  });

  return { hasLogfmt, hasJSON };
}