如何更新/替换 Angular Material Tree 中的数据

Question

我试图在材料平面树组件中实现搜索功能（过滤），但是当我更新数据源时没有任何反应。我感觉我已经尝试了所有不同的方法，但无法使其发挥作用。我想做的就是替换数据并重新渲染树。我究竟做错了什么？

我尝试过不同的解决方案，但许多似乎已经过时，例如：

this.dataSource.data = null;
    this.dataSource = new MatTreeFlatDataSource(this.treeControl, this.treeFlattener);
    this.dataSource.data = [];

当尝试展平空对象时会出现错误。

interface FlatNode {
  expandable: boolean;
  name: string;
  level: number;
}

@Component({
  selector: 'app-category-list',
  templateUrl: './category-list.component.html',
  styleUrls: ['./category-list.component.scss']
})
export class CategoryListComponent {
  dataChange = new BehaviorSubject<Category[]>([]);
  private _transformer = (node: Category, level: number) => {
    return {
      expandable: !!node.children && node.children.length > 0,
      name: node.name,
      level: level,
    };
  }

  treeControl = new FlatTreeControl<FlatNode>(
      node => node.level, node => node.expandable);

  treeFlattener = new MatTreeFlattener(
      this._transformer, node => node.level, node => node.expandable, node => node.children);

  dataSource = new MatTreeFlatDataSource(this.treeControl, this.treeFlattener);

  constructor(private categoryListService: CategoryListService) {this.dataSource.data = this.categoryListService.getTopCategories();}

  hasChild = (_: number, node: FlatNode) => node.expandable;

  ngOnInit() {
    this.dataChange.subscribe(data => {
      this.dataSource.data = data;
    });
  }

  }

  searchCategory(list: Category[]) {
    this.dataChange.next(list);
  }
}

我希望数据源更新并重新渲染材质树。