Method _subscribeToDataChanges

src/cdk/tree/tree.ts:372–399

Set up a subscription for the data provided by the data source.

()

  /** Set up a subscription for the data provided by the data source. */
  private _subscribeToDataChanges() {
    if (this._dataSubscription) {
      return;
    }

    let dataStream: Observable<readonly T[]> | undefined;

    if (isDataSource(this._dataSource)) {
      dataStream = this._dataSource.connect(this);
    } else if (isObservable(this._dataSource)) {
      dataStream = this._dataSource;
    } else if (Array.isArray(this._dataSource)) {
      dataStream = observableOf(this._dataSource);
    }

    if (!dataStream) {
      if (typeof ngDevMode === 'undefined' || ngDevMode) {
        throw getTreeNoValidDataSourceError();
      }
      return;
    }

    this._dataSubscription = this._getRenderData(dataStream)
      .pipe(takeUntil(this._onDestroy))
      .subscribe(renderingData => {
        this._renderDataChanges(renderingData);
      });
  }

  /** Given an Observable containing a stream of the raw data, returns an Observable containing the RenderingData */
  private _getRenderData(dataStream: Observable<readonly T[]>): Observable<RenderingData<T>> {