Method _render

src/cdk/table/table.ts:996–1041

Renders the table if its state has changed.

()

  /** Renders the table if its state has changed. */
  private _render(): void {
    // Cache the row and column definitions gathered by ContentChildren and programmatic injection.
    this._cacheRowDefs();
    this._cacheColumnDefs();

    // Make sure that the user has at least added header, footer, or data row def.
    if (
      !this._headerRowDefs.length &&
      !this._footerRowDefs.length &&
      !this._rowDefs.length &&
      (typeof ngDevMode === 'undefined' || ngDevMode)
    ) {
      throw getTableMissingRowDefsError();
    }

    // Render updates if the list of columns have been changed for the header, row, or footer defs.
    const columnsChanged = this._renderUpdatedColumns();
    const rowDefsChanged = columnsChanged || this._headerRowDefChanged || this._footerRowDefChanged;
    // Ensure sticky column styles are reset if set to `true` elsewhere.
    this._stickyColumnStylesNeedReset = this._stickyColumnStylesNeedReset || rowDefsChanged;
    this._forceRecalculateCellWidths = rowDefsChanged;

    // If the header row definition has been changed, trigger a render to the header row.
    if (this._headerRowDefChanged) {
      this._forceRenderHeaderRows();
      this._headerRowDefChanged = false;
    }

    // If the footer row definition has been changed, trigger a render to the footer row.
    if (this._footerRowDefChanged) {
      this._forceRenderFooterRows();
      this._footerRowDefChanged = false;
    }

    // If there is a data source and row definitions, connect to the data source unless a
    // connection has already been made.
    if (this.dataSource && this._rowDefs.length > 0 && !this._renderChangeSubscription) {
      this._observeRenderChanges();
    } else if (this._stickyColumnStylesNeedReset) {
      // In the above case, _observeRenderChanges will result in updateStickyColumnStyles being
      // called when it row data arrives. Otherwise, we need to call it proactively.
      this.updateStickyColumnStyles();
    }

    this._checkStickyStates();
  }

  /**
   * Get the list of RenderRow objects to render according to the current list of data and defined