嵌套ngFor循环中索​​引的多次迭代

Question

我对ngFor循环中的迭代项使用trackByIndex函数：

trackByIndex(index: number, obj: any): any {
  return index;
}

以下是我的代码如何使用它的简短示例：

<div *ngFor="let comment of comments; let i = index; trackBy: trackByIndex">
  {{ i, comment.text }}
  <div *ngFor="let answer of comment.answers; let j = index; trackBy: trackByIndex">{{ j, answer.text }}</div>
</div>

但是当我的页面上有2个comment个项目时，我会在每个评论中都有相同的迭代答案：

"comment 1": {
    "answer 1",
    "answer 2"
},
"comment 2": {
    "answer 1", // should be answer 3
    "answer 2" // should be answer 4
}

我怎样才能解决这个问题？非常感谢任何提示。

Answer 1

我想，你错过了ngFor

的绑定

尝试使用

<div *ngFor="let comment of comments; let i = index; trackBy: trackByIndex">
  {{ i, comment.text }}
  <div *ngFor="let answer of comment.answers; let j = index; trackBy: trackByIndex">{{ j, answer.text }}</div>
</div>