Angular 2：儿童的递归模板

Question

我正在反对的API为我提供了以下结构：

"data": [
{
  "id": 5,
  "name": "First name",
  "parent": 0
},
{
  "id": 1,
  "name": "Second name",
  "parent": 5
},
{
  "id": 6,
  "name": "Third name",
  "parent": 1
},
{
  "id": 15,
  "name": "Fourth name",
  "parent": 0
},
{
  "id": 25,
  "name": "Fifth name",
  "parent": 5
}
]

我想使用支持无限数量的子级别的ngFor围绕此构建树结构。

这是我到目前为止所尝试的：

<div *ngFor="let d1 of _dataList">
<ul *ngIf="d1.parent == 0">
    <li>
        {{d1.name}}
        <ul *ngFor="let d2 of _dataList">
            <li *ngIf="d2.parent == d1.id">{{d2.name}}</li>
        </ul>
    </li>
</ul>
</div>

这是有效的，但它很难看，我必须手动重复这个X级别的数据，从而留下硬编码限制。

如何优化此代码以支持无限级别 - 并且看起来更好？

Answer 1

你可以有一个recusive组件，比如名为TreeComponent的组件，TreeComponent的模板就像这样

<div *ngFor="let item of dataList">
  <ul *ngIf="item.parent==parentId">
    <li>{{item.name}}
      <tree [parentId]="item.id" [dataList]="removeCurrentLevelItems(dataList,parentId)"></tree>
    </li>
  </ul>
</div>

查看link here的现场演示

Answer 2

https://stackblitz.com/edit/angular-yij5e5?file=src%2Fapp%2Ftree-view%2Ftree-view.component.ts注意：下面的代码不是递归的，它是2d，不能用于树渲染。您应该使用ng模板或为其定义组件。

<div *ngFor="let d1 of _dataList">
<ul *ngIf="d1.parent == 0">
    <li>
        {{d1.name}}
        <ul *ngFor="let d2 of _dataList">
            <li *ngIf="d2.parent == d1.id">{{d2.name}}</li>
        </ul>
    </li>
</ul>
</div>

• 来自http://odyniec.net/articles/turning-lists-into-trees/的css
• 角度来自https://gist.github.com/arniebradfo/5cf89c362cc216df6fc1d9ca4d536b72
• js（如何将平面数组转换为树）来自我：D

[解决方案1] =>

JS

let xTree = [{
                "id": 5,
                "name": "First name",
                "parent": 0
            },
            ...
        ];
        let tree = [{
            id: 0,
            name: 'root',
            parent: null,
            childs: []
        }];
        let todoList = [];
        Converter();
        function FindParent(list, el) {
            if (list.length > 0) {
                let res = list.find(x => x.id === el.parent);
                if (res) {
                    return res;
                } else {
                    let _res = undefined;
                    list.forEach(xchild => {
                        _res = FindParent(xchild.childs, el);
                        if (res)
                            return _res;
                    });
                    return _res
                }
            } else {
                return undefined;
            }
        }

        function Converter() {
            todoList = xTree;
            for (let x = 0; x < 90; x++) {
                todoList.forEach(r => {
                    let parent = FindParent(tree, r);
                    if (parent) {
                        if (!parent.childs) {
                            parent.childs = [];
                        }
                        parent.childs.push(r);
                        todoList = todoList.filter(el => el !== r);
                    }
                });
            }
        }

HTML

<ul class="tree">
  <ng-template #recursiveList let-list="list">
    <li *ngFor="let item of list">
      {{item.name}}
      <ul *ngIf="item.childSet.length > 0">
        <ng-container *ngTemplateOutlet="recursiveList; context:{ list: item.data}"></ng-container>
      </ul>
    </li>
  </ng-template>
  <ng-container *ngTemplateOutlet="recursiveList; context:{ list: data}"></ng-container>
</ul>

CSS

ul.tree, ul.tree ul {
  list-style-type: none;
}
  ul.tree, ul.tree ul {
    list-style-type: none;
    background: url(/assets/vline.png) repeat-y;
    margin: 0;
    padding: 0;
  }

    ul.tree ul {
      margin-left: 10px;
    }

    ul.tree li {
      margin: 0;
      padding: 0 12px;
      line-height: 20px;
      background: url(/assets/node.png) no-repeat;
      color: #369;
      font-weight: bold;
    }

      ul.tree li:last-child {
        background: #fff url(/assets/lastnode.png) no-repeat;
      }