在ngFor中显示特定的Div

Question

我有一堆使用ngFor和用户信息的卡片。卡内有一个按钮，用于显示该特定用户的旅行信息。

我用初始状态display: none创建了一个div。我想在点击时使用ngStyle绑定display: block属性，但问题是所有的div都显示出来，而不仅仅是我需要的特定div。

有关如何做到这一点的任何建议？

HTML

<div class="col s12 m6 l4" *ngFor="let student of students; let i = index">
   <i class="material-icons" (click)="showBox()">access_alarm</i>

   <div class="travel-info" [ngStyle]="{'display': boxDisplay == true ? 'block' : 'none'}" >
      <app-travel-info ></app-travel-info>
   </div>
</div>

TS

boxDisplay = false;

showBox() {
    this.boxDisplay = true;
}

Answer 1

您可以使用@ViewChildren。我给你这个例子：

你的HTML：

<div class="student-container" *ngFor="let s of students; let i = index">
  <span>Name: {{s.name}} - Index: {{i}}</span>
  <div class="student-box" #boxes>
    <span>Hey! I'm opened.</span>
    <span>My Secret Number is: {{s.secretNumber}}</span>
  </div>
  <button (click)="toggleBox(i)">Click Me!</button>
</div>

你的组件：

import { Component, ViewChildren, QueryList, ElementRef } from "@angular/core";

@Component({
  selector: "app-root",
  templateUrl: "./app.component.html",
  styleUrls: ["./app.component.css"]
})
export class AppComponent {
  @ViewChildren("boxes") private boxes: QueryList<ElementRef>;

  students = [
    { name: "Peter", secretNumber: "88" },
    { name: "Laura", secretNumber: "45" },
    { name: "Paul", secretNumber: "13" }
  ];

  toggleBox(index) {
    let nativeElement = this.boxes.toArray()[index].nativeElement;
    nativeElement.style.display =
      nativeElement.style.display === "none" || !nativeElement.style.display
        ? "block"
        : "none";
  }
}

你的CSS：

.student-container {
  background: lightblue;
  margin: 10px;
  padding: 10px;
}

.student-box {
  display: none;
}

https://codesandbox.io/s/zwqoxp583x

Answer 2

你需要有一个属性显示学生数组的每个元素，然后根据索引启用/禁用，

<div class="col s12 m6 l4" *ngFor="let student of students; let i = index">
   <i class="material-icons" (click)="showBox(student)">access_alarm</i>
   <div class="travel-info" [ngStyle]"{'display': student.boxDisplay == true ? 'block' : 'none'}" >
      <app-travel-info ></app-travel-info>
   </div>
</div>


showBox(student:any) {
    student.boxDisplay = true;
}

Answer 3

问题是你只有一个为所有变量设置的变量。

你会想重构showBox是这样的。

TS

this.boxDisplay = this.students.map(s => false);

showBox(index) {
  this.boxDisplay[index] = true;
}

HTML

<div class="col s12 m6 l4" *ngFor="let student of students; let i = index">
   <i class="material-icons" (click)="showBox(i)">access_alarm</i>

   <div class="travel-info" [ngStyle]="{'display': boxDisplay[i] == true ? 'block' : 'none'}" >
      <app-travel-info ></app-travel-info>
   </div>
</div>

如果是我，我会使用ngIf而不是ngStyle。

<div class="col s12 m6 l4" *ngFor="let student of students; let i = index">
   <i class="material-icons" (click)="showBox(i)">access_alarm</i>

   <div class="travel-info" *ngIf="boxDisplay[i]" >
      <app-travel-info ></app-travel-info>
   </div>
</div>