问matSort在mat-table角度中不能正常工作

EN

<mat-table [dataSource]="dataSource" padding matSort>

  <ng-container matColumnDef="uid">
    <!--<mat-header-cell *matHeaderCellDef mat-sort-header>Building UID</mat-header-cell>-->
    <mat-header-cell *matHeaderCellDef mat-sort-header>
      Building UID
    </mat-header-cell>
    <mat-cell *matCellDef="let tree" padding>{{tree.uid}}</mat-cell>
  </ng-container>

  <ng-container matColumnDef="address">
    <mat-header-cell *matHeaderCellDef mat-sort-header>
      Address
    </mat-header-cell>
    <mat-cell *matCellDef="let tree" padding>{{tree.location.address}}</mat-cell>
  </ng-container>

  <ng-container matColumnDef="zipCode">
    <mat-header-cell *matHeaderCellDef mat-sort-header>
      Zip code
    </mat-header-cell>
    <mat-cell *matCellDef="let tree" padding>{{tree.location.zipCode}}</mat-cell>
  </ng-container>

  ...

  <mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>

  <mat-row *matRowDef="let row; columns: displayedColumns"></mat-row>

</mat-table>

@Component({
  selector: 'page-buildings',
  templateUrl: 'buildings.html',
})
export class BuildingsPage {
  @ViewChild(MatSort) sort: MatSort;
  ...
  private displayedColumns: string[] = ["uid", "address", "zipCode", "city", "country", "treeDetails"]; // tslint:disable-line
  private dataSource: MatTableDataSource<any>;

  ...
  constructor(...) {

    this.dataSource = new MatTableDataSource(...);
    this.dataSource.sort = this.sort;
  }
  ...
}