DataTable没有刷新角度

Question

<div class="row-fluid padTop5">
  <div class="col-12">
    <div class="row" *ngIf="showFiles">
      <div class="col-12 colBorder">
        <table datatable class="table table-striped centerAlign">
          <thead>
            <tr>
              <th class="centerAlign">Select All<input type="checkbox" [(ngModel)]="fileSelectAll" name="fileSelectAll" class="d-block" (change)="selectAll($event,fileSelectAll)"></th>
              <th>TestCase Name</th>
              <!-- <th>Provision Name</th> -->
            </tr>
          </thead>
          <tbody>
            <tr *ngFor="let file of fileList;let i =index">
              <td>
                <input type="checkbox" [(ngModel)]="file.selected" [checked]="isSelected" (change)='checkClicked($event,file)' name="cb">
              </td>
              <td>{{file.name}}</td>
              <!-- <td>PE</td> -->
            </tr>
          </tbody>
        </table>
      </div>
    </div>
  </div>
</div>

我正在使用角度数据表..当用户第一次从local.works中选择文件时，表格正在形成..但是当用户再次选择文件时，以前的记录没有消失..如何。刷新表格