我在折叠表格行数据时遇到问题。当我单击按钮时，它将切换所有子行，而不是恰好是子行。这是代码段：

    <table class="table table-bordered table-hover">
      <thead>
        <tr>
          <th class="">Үйлчилгээний ангилал</th>
          <th class="">Код</th>
          <th class="">Үйлчилсэн тоо</th>
          <th class="">Зарцуулсан мин</th>
          <th class="">Зорилт</th>
          <th class="">Зорилт нөхөх</th>
        </tr>
      </thead>
      <tbody *ngFor="let item of nodes; let i = index">
        <tr>
          <td>
            <button
              *ngIf="item.children.length > 0"
              (click)="getchild($event,item.id)"
            >
              <i class="icon-arrow-right5"></i>
            </button>
            {{ item.name }}
          </td>
          <td>{{ item.code }}</td>
          <td>{{ item.count }}</td>
          <td>{{ item.elapsed }}</td>
          <td>{{ item.goal }}</td>
          <td>{{ item.children.length }}</td>
        </tr>
        <tr
          *ngFor="let child of item.children"
          [ngClass]="toggleChild ? 'expand' : 'collapse'"
        >
          <td>{{ child.name }}</td>
          <td>{{ child.code }}</td>
          <td>{{ child.elapsed }}</td>
          <td>{{ child.goal }}</td>
          <td>{{ child.goal }}</td>
          <td>{{ child.goal }}</td>
        </tr>
      </tbody>
    </table>

还有我的打字稿文件：

nodes = [
    {
      id: 1,name: "Санхүү",code: "-",count: "986",elapsed: "08:29",goal: "92%",children: [
        {
          id: 1,name: "Данс нээх харилцах",code: "5545",goal: "92%"
        },{
          id: 2,name: "Карт захиалах",code: "4587",goal: "82%"
        }
      ]
    },{
      id: 2,name: "Санхүүгийн бус",goal: "80%",{
      id: 3,name: "Дундаж",children: []
    }
  ];
  options = {};

  private getchild(e: any,id: any) {
    this.toggleChild = !this.toggleChild;
    e.stopPropagation();
  }

上面的代码工作正常，但是当我单击按钮时，整个孩子tr展开了。我究竟做错了什么？我真正想要的是，当我单击按钮时，它只会扩展自己的孩子。