Angular 在嵌套 *ngFor 中将索引从父级传递给子级

Question

我想显示带有一堆嵌套 *ngFor 循环的内容，并且我想跟踪前一个 ngFor 循环的索引作为父索引。我找不到将上一个循环的索引传递给当前循环的方法。

这是我尝试的方法（无效）：

<div *ngFor="let parent of content; index as i" > 
    <span>{{parent.name}} index - {{i}}</span>
        <div *ngFor="let child of parent.childreen; i as parentIndex, index as i"  >
            <span>{{child.name}} index - {{i}} parentIndex - {{parentIndex}}   </span>
            <div *ngFor="let child of child.childreen; i as parentIndex, index as i">
                <span>{{child}} index - {{i}} parentIndex - parentIndex</span>
            </div>
        </div>
</div>

有什么方法可以让我像上面那样将之前的 index 添加到 parentIndex 变量？

这是我想要实现的示例输出。

Parent 1 index - 0
Child 1.1 index - 0 parentIndex - 0
Child 1.1.1 index - 0 parentIndex - 0
Child 1.1.2 index - 1 parentIndex - 0
Child 1.1.3 index - 2 parentIndex - 0
Child 1.2 index - 1 parentIndex - 0
Child 1.2.1 index - 0 parentIndex - 1
Child 1.2.2 index - 1 parentIndex - 1
Child 1.2.3 index - 2 parentIndex - 1

Parent 2 index - 1
Child 2.1 index - 0 parentIndex - 1
Child 2.1.1 index - 0 parentIndex - 0
Child 2.1.2 index - 1 parentIndex - 0
Child 2.1.3 index - 2 parentIndex - 0
Child 2.2 index - 1 parentIndex - 1
Child 2.2.1 index - 0 parentIndex - 1
Child 2.2.2 index - 1 parentIndex - 1
Child 2.2.3 index - 2 parentIndex - 1

这是我使用的对象示例

  content: any[] = [
    {
      name: "Parent 1",
      childreen: [        
        {
        name: "Child 1.1",
        childreen: ["Child 1.1.1", "Child 1.1.2", "Child 1.1.3"]
      }, {
        name: "Child 1.2",
        childreen: ["Child 1.2.1", "Child 1.2.2", "Child 1.2.3"]
      }]
    }, {
      name: "Parent 2",
      childreen: [
        {
          name: "Child 2.1",
          childreen: ["Child 2.1.1", "Child 2.1.2", "Child 2.1.3"]
        }, {
          name: "Child 2.2",
          childreen: ["Child 2.2.1", "Child 2.2.2", "Child 2.2.3"]
        }
      ]
    }
  ]

Answer 1

只需为每个 *ngFor 的索引使用不同的局部变量名称即可。

<div *ngFor="let parent of content; index as i">
  <span>{{parent.name}} index - {{i}}</span>
  <div *ngFor="let child of parent.childreen; index as j">
    <span>{{child.name}} index - {{j}} parentIndex - {{i}}</span>
    <div *ngFor="let child of child.childreen; index as k">
      <span>{{child}} index - {{k}} parentIndex - {{i}} </span>
    </div>
  </div>
  <br>
</div>

更新

工作示例：Stackblitz

Angular 在嵌套 *ngFor 中将索引从父级传递给子级

Angular passing index from parent to child in nested *ngFor

angular

ngfor

更新