tsdb-kit/src/connectors/sql.ts

import { DatasourceConnector, Datasource, DatasourceQuery, DataTable } from '.';
import { processSQLLimitOffset } from './utils';

import * as _ from 'lodash';

// as of 26.09.2020, it works for all SQL datasources
export class SqlConnector extends DatasourceConnector {
  private _targetName: string; //save first target name, while multi metric not implemented
  private url: string;

  constructor(datasource: Datasource, targets: any[]) {
    super(datasource, targets);

    this.url = datasource.url;

    if(targets.length === 0) {
      throw Error('got empty targets list');
    }
    this._targetName = targets[0].refId;
  }

  getQuery(from: number, to: number, limit: number, offset: number): DatasourceQuery {
    let queries = this.targets;

    _.forEach(queries, q => {
      q.rawSql = processSQLLimitOffset(q.rawSql, limit, offset);
      if (!q.datasourceId) {
        q.datasourceId = this.datasource.datasourceId;
      }
    });

    return {
      url: this.url,
      method: 'POST',
      schema: {
        data: {
          from: String(from),
          to: String(to),
          queries: queries,
        }
      }
    };
  }

  parseResponse(res): DataTable {
    let emptyResult = {
      columns: ['timestamp', 'target'],
      values: []
    };

    if(res.data === undefined || res.data.results.length < 1) {
      console.log('datasource return empty response, no data');
      return emptyResult;
    }

    // TODO: support more than 1 metric (each res.data.results item is a metric)
    let results = res.data.results[this._targetName];
    if (_.isEmpty(results.frames)) {
      return emptyResult;
    }

    const frame = results.frames[0];
    return {
      columns: frame.schema.fields.map(field => field.name),
      // @ts-ignore
      values:  _.zip(...frame.data.values),
    };
  }
}