从 Angular 6 材质树中的子节点获取父层次结构

Question

我正在关注tutorial 以 6 角实现 cdk 树。我创建了一个树结构，现在我想通过使其可点击来从子级获取父层次结构，同时有诸如 getDescendants 之类的方法来获取子级节点，反之亦然不可用。如何从子节点或叶节点获取父层次结构。

Answer 1

我已将这些方法添加到我的树组件中。请注意，我使用的是扁平树，这不适用于嵌套树。

@Component({
  selector: 'es-outline-tree',
  // ...
})
export class OutlineTreeComponent implements OnInit {
  treeControl: FlatTreeControl<FlatTreeNode>;

  // other code...

  /**
   * Recursively expand all parents of the passed node.
   */
  expandParents(node: FlatTreeNode) {
    const parent = this.getParent(node);
    this.treeControl.expand(parent);

    if (parent && parent.level > 0) {
      this.expandParents(parent);
    }
  }

  /**
   * Iterate over each node in reverse order and return the first node that has a lower level than the passed node.
   */
  getParent(node: FlatTreeNode) {
    const { treeControl } = this;
    const currentLevel = treeControl.getLevel(node);

    if (currentLevel < 1) {
      return null;
    }

    const startIndex = treeControl.dataNodes.indexOf(node) - 1;

    for (let i = startIndex; i >= 0; i--) {
      const currentNode = treeControl.dataNodes[i];

      if (treeControl.getLevel(currentNode) < currentLevel) {
        return currentNode;
      }
    }
  }
}

我打算创建自己的FlatTreeControl（通过扩展 Angular CDK 的FlatTreeControl）并将这个逻辑移到那里。

更新

我已将上述逻辑移至我自己的 FlatTreeControl 实现中：

import { FlatTreeControl } from '@angular/cdk/tree';

export class CustomTreeControl<T> extends FlatTreeControl<T> {
  /**
   * Recursively expand all parents of the passed node.
   */
  expandParents(node: T) {
    const parent = this.getParent(node);
    this.expand(parent);

    if (parent && this.getLevel(parent) > 0) {
      this.expandParents(parent);
    }
  }

  /**
   * Iterate over each node in reverse order and return the first node that has a lower level than the passed node.
   */
  getParent(node: T) {
    const currentLevel = this.getLevel(node);

    if (currentLevel < 1) {
      return null;
    }

    const startIndex = this.dataNodes.indexOf(node) - 1;

    for (let i = startIndex; i >= 0; i--) {
      const currentNode = this.dataNodes[i];

      if (this.getLevel(currentNode) < currentLevel) {
        return currentNode;
      }
    }
  }
}

Answer 2

感谢 Flauwekeul，稍微简化了一点

import { FlatTreeControl } from '@angular/cdk/tree';

export class CustomTreeControl<T> extends FlatTreeControl<T> {
  /**
   * Iterate over each node in reverse order and expand each inferior level nodes until level 0.
   */
  expandParents(node: any) {
      const currentLevel = this.getLevel(node);

      if (currentLevel < 1) {
          return null;
      }

      const startIndex = this.dataNodes.indexOf(node) - 1;

      for (let i = startIndex; i >= 0; i--) {
          const currentNode = this.dataNodes[i];

          if (this.getLevel(currentNode) < currentLevel) {
              this.expand(currentNode);
              if (this.getLevel(currentNode) === 0) break;
          }
      }
  }
}

Answer 3

父层次结构可以存储在数字数组中，其中每个数字是重复嵌套节点的索引。为了在指定节点上展开树，我尝试使用前面的示例，但最终我决定这样做：

1) 每次点击节点都必须调用 ChangePath：

changePath(node) {
if (node.level < this.nodePath.length) {
  this.nodePath.splice(node.level, this.nodePath.length - node.level);
}
this.nodePath.push(this.treeControl.dataNodes.indexOf(node));}

2）接下来，当树崩溃时，我们必须调用nodePath中每个项目的展开（当树崩溃是由于删除节点我们不想展开它时，所以从路径中删除最后一个元素）：

expandTreeOnSpecifiedNode(isDelete: boolean) {
  if (isDelete) {
    this.nodePath.pop();
  }
  this.nodePath.forEach(id => {
    console.log(id);
    this.treeControl.expand(this.treeControl.dataNodes[id]);
    });
  }