grafana/public/app/plugins/datasource/dashboard/datasource.ts

import { Observable, defer, finalize, map, of } from 'rxjs';

import {
  DataSourceApi,
  DataQueryRequest,
  DataQueryResponse,
  DataSourceInstanceSettings,
  TestDataSourceResponse,
} from '@grafana/data';
import { SceneDataProvider, SceneDataTransformer, SceneObject } from '@grafana/scenes';
import { findVizPanelByKey, getVizPanelKeyForPanelId } from 'app/features/dashboard-scene/utils/utils';

import { DashboardQuery } from './types';

/**
 * This should not really be called
 */
export class DashboardDatasource extends DataSourceApi<DashboardQuery> {
  constructor(instanceSettings: DataSourceInstanceSettings) {
    super(instanceSettings);
  }

  getCollapsedText(query: DashboardQuery) {
    return `Dashboard Reference: ${query.panelId}`;
  }

  query(options: DataQueryRequest<DashboardQuery>): Observable<DataQueryResponse> {
    const scene: SceneObject | undefined = options.scopedVars?.__sceneObject?.value;

    if (options.requestId.indexOf('mixed') > -1) {
      throw new Error('Dashboard data source cannot be used with Mixed data source.');
    }

    if (!scene) {
      throw new Error('Can only be called from a scene');
    }

    const query = options.targets[0];
    if (!query) {
      return of({ data: [] });
    }

    const panelId = query.panelId;

    if (!panelId) {
      return of({ data: [] });
    }

    let sourcePanel = this.findSourcePanel(scene, panelId);

    if (!sourcePanel) {
      return of({ data: [], error: { message: 'Could not find source panel' } });
    }

    let sourceDataProvider: SceneDataProvider | undefined = sourcePanel.state.$data;

    if (!query.withTransforms && sourceDataProvider instanceof SceneDataTransformer) {
      sourceDataProvider = sourceDataProvider.state.$data;
    }

    if (!sourceDataProvider || !sourceDataProvider.getResultsStream) {
      return of({ data: [] });
    }

    return defer(() => {
      if (!sourceDataProvider!.isActive && sourceDataProvider?.setContainerWidth) {
        sourceDataProvider?.setContainerWidth(500);
      }

      const cleanUp = sourceDataProvider!.activate();

      return sourceDataProvider!.getResultsStream!().pipe(
        map((result) => {
          return {
            data: result.data.series,
            state: result.data.state,
            errors: result.data.errors,
            error: result.data.error,
            key: 'source-ds-provider',
          };
        }),
        finalize(cleanUp)
      );
    });
  }

  private findSourcePanel(scene: SceneObject, panelId: number) {
    return findVizPanelByKey(scene, getVizPanelKeyForPanelId(panelId));
  }

  testDatasource(): Promise<TestDataSourceResponse> {
    return Promise.resolve({ message: '', status: '' });
  }
}