如何制作 mat-tree 组件 Angular 材料 6.0.1

Question

我正在尝试做一个材料 angular 基于 mat-tree 的应用程序但是当我运行此代码时它没有显示值并且我没有收到任何错误我该如何解决这个帮助我继续前进

当我们打开应用程序时，我们需要显示 class 名称

下面我添加了我的 html 和组件代码

<mat-nested-tree-node *matTreeNodeDef="let node; when: hasNestedChild">
    <li>
      <div class="mat-tree-node">
        <button mat-icon-button matTreeNodeToggle
                [attr.aria-label]="'toggle ' + node.filename">
          <mat-icon class="mat-icon-rtl-mirror">
            {{nestedTreeControl.isExpanded(node) ? 'expand_more' : 'chevron_right'}}
          </mat-icon>
        </button>

      </div>
      <ul [class.example-tree-invisible]="!nestedTreeControl.isExpanded(node)">
        <ng-container matTreeNodeOutlet></ng-container>
      </ul>
    </li>
  </mat-nested-tree-node>

零件：

const TREE_DATA = [
{
    "class":"ece",
    "count":60,
    "students": [

            {"name":"a","id":"11"},
            {"name":"b","id":"12"},
            {"name":"c","id":"13"},
            {"name":"d","id":"14"}

    ]
},
{
    "class":"mech",
    "count":60,
    "students": [

            {"name":"r","id":"21"},
            {"name":"e","id":"22"},
            {"name":"w","id":"23"},
            {"name":"q","id":"24"}

    ]
}
];


@Injectable()
export class FileDatabase {
  dataChange = new BehaviorSubject<FileNode[]>([]);

  get data(): FileNode[] { return this.dataChange.value; }

  constructor() {
    this.initialize();
  }

  initialize() {

    const dataObject = TREE_DATA;


    const data = this.buildFileTree(dataObject, 0);


    this.dataChange.next(data);
  }


  buildFileTree(obj: object, level: number): FileNode[] {
    return Object.keys(obj).reduce<FileNode[]>((accumulator, key) => {
      const value = obj[key];
      const node = new FileNode();
      node.filename = key;

      if (value != null) {
        if (typeof value === 'object') {
          node.children = this.buildFileTree(value, level + 1);
        } else {
          node.type = value;
        }
      }

      return accumulator.concat(node);
    }, []);
  }
}

/**
 * @title Tree with nested nodes
 */
@Component({
  selector: 'tree-nested-overview-example',
  templateUrl: 'tree-nested-overview-example.html',
  styleUrls: ['tree-nested-overview-example.css'],
  providers: [FileDatabase]
})
export class TreeNestedOverviewExample {
  nestedTreeControl: NestedTreeControl<FileNode>;
  nestedDataSource: MatTreeNestedDataSource<FileNode>;

  constructor(database: FileDatabase) {
    this.nestedTreeControl = new NestedTreeControl<FileNode>(this._getChildren);
    this.nestedDataSource = new MatTreeNestedDataSource();

    database.dataChange.subscribe(data => this.nestedDataSource.data = data);
  }

  hasNestedChild = (_: number, nodeData: FileNode) => !nodeData.type;

  private _getChildren = (node: FileNode) => node.children;
}

这是我的演示

当我打开页面时，它应该是这样的

当我点击 ece 它应该是这样的

Answer 1

它添加了{{node：json}}以下的内容，您只需要从节点对象中获取正确的数据。

    <button mat-icon-button matTreeNodeToggle
            [attr.aria-label]="'toggle ' + node.filename">
      <mat-icon class="mat-icon-rtl-mirror">
        {{nestedTreeControl.isExpanded(node) ? 'expand_more' : 'chevron_right'}}
      </mat-icon>
      {{node | json}}
    </button>

Answer 2

<mat-tree>
    <mat-tree-node> Parent node name </mat-tree-node>
    <mat-tree-node> Child Node 1 </mat-tree-node>
    <mat-tree-node> Child Node 2 </mat-tree-node>
</mat-tree>