以编程方式选择行ag-grid angular 2

尝试在ag-grid中默认选择第一行.根据ag-grid文档,我应该可以使用NodeSELEction Api( https://www.ag-grid.com/javascript-grid-selection/?framework=all#gsc.tab=0)来完成此操作.但我根本无法访问节点对象.
HTML文件

<div class="pulldown panel panel-default">
          <div class="panel-heading">{{rulesSumMarytitlE}}</div>
          <ag-grid-angular #agGrid   class="ag-fresh ag-bootstrap"
                           [gridoptions]="gridoptions"
                           [rowData]="rowData"
                           [columnDefs]="columnDefs"
                           [enableSorTing]="true"
                           rowSELEction="single"
                           [pagination]="true"
                           [suppressCellSELEction]="true"
                           (gridReady)="onGridReady($event)"
                           (rowSELEcted)="onRowSELEct($event)">
          </ag-grid-angular>
      </div>

我在“onGridReady”方法中调用节点选择api但错误输出错误消息“无法调用setSELEcted on undefined”.

public onGridReady(event: any): void {
    event.api.sizecolumnsToFit();
    this.gridoptions.api.node.setSELEcted(true);
  }

public onGridReady(event: any): void {
    event.api.sizecolumnsToFit();
    gridoptions.api.forEachNode(node=> node.rowIndex ? 0 : node.setSELEcted(true))
  }