如何在Angular 2中选择ngFor中的所有过滤复选框？

Question

我有一个Angular 2组件,它可以加载并向用户显示一个复选框*ngFor列表,也可以根据键过滤列表.我需要选择所有过滤的项目并将它们添加到数组中.我可以检查所有复选框,但问题是当我更改checked问题时change事件不会触发,任何想法如何解决这个问题？

模板:

<div class="form-group">
    <input type="text" class="form-control" id="stringKeyFilter" placeholder="Key Filter"
           [(ngModel)]="keyFilter">
</div>

<table class="table table-striped table-hover">
    <thead>
    <tr>
        <th>Id</th>
        <th style="width: 150px;">Action</th>
    </tr>
    </thead>
    <tbody>
    <tr *ngFor="let device of devices| stringFilter: keyFilter">
        <td>
            {{device.$key}}
        </td>
        <td>
            <div class="checkbox">
                <label> <input type="checkbox"
                               [checked]="selectAll || selectedDevices.indexOf(device.$key) > -1"
                               (change)="updateSelectedDevices(device.$key, $event)" > View</label>
            </div>
        </td>
    </tr>
    </tbody>
</table>

<div class="btn-group pull-right">
    <button type="button" class="btn btn-primary" (click)="selectAllDevices()">Select All</button>
    <button type="button" class="btn btn-default" (click)="deselectAllDevices()">Deselect All
    </button>
</div>

零件:

@Component({
    moduleId: module.id,
    selector: 'device-list',
    template: template
})
export class DeviceListComponent implements OnInit {
    devicesObservable: FirebaseListObservable<Device[]>;
    devices: Device[] = [];
    isLoading: boolean = true;
    selectedDevices: string[] = [];
    selectAll: boolean = false;
    allCtrl: any;

    keyFilter: string = '';

    constructor(private af: AngularFire) {

    }

    ngOnInit(): void {


        this.devicesObservable = this.af.database.list('/online', {
            query: {
                orderByKey: true,
            }
        });
        this.devicesObservable.subscribe((devicesData)=> {
            this.devices = devicesData;
            this.isLoading = false
        });
    }

    updateSelectedDevices(deviceId: string, event): void {
        if (event.target.checked) {
            this.selectedDevices.push(deviceId);
        }
        else {
            _.pull(this.selectedDevices, deviceId);
        }
    }


    loadingDeviceDetail(loading: boolean): void {
        this.isLoading = loading;
    }

    selectAllDevices(): void {
        this.selectAll = true;
    }

    deselectAllDevices(): void {
        this.selectAll = false;
        this.selectedDevices = [];
    }

}

Answer 1

更新

更新了示例代码和plunker以演示选择/取消选中已筛选列表的所有复选框.

根据我的理解,过滤器行为从Angular1变为Angular2.

在Angular1中,当修改数据或过滤器参数时,将重新计算DOM(网页).(我可能在很久以前就错了:P)

在Angular2中,简而言之,修改数据(数组)不会触发过滤器计算,因此没有新结果,也没有更新到DOM.

这里有漫长而官方的解释:Angular2 Pipes - ts.如果您坚持在模板中使用管道(过滤器),则应探索文档中的不纯管道部分.

另一种解决方案是不使用过滤器*ngFor.改为创建筛选列表.

Plunker

http://plnkr.co/edit/pEpaj0?p=preview

示例代码

app.component.ts

import {Component} from '@angular/core';
import {bootstrap} from '@angular/platform-browser-dynamic';

@Component({
  selector: 'material-app',
  templateUrl: 'app.component.html'
})
export class AppComponent {

  title='How to select all filtered checkboxes inside ngFor in Angular 2?';
  url='http://stackoverflow.com/questions/39703103/';

  device = [
    {'name':'abc','checked':false},
    {'name':'abcd','checked':false},
    {'name':'abcde','checked':false},
    {'name':'abc123','checked':false},
    {'name':'abc1234','checked':false}];

  deviceFilter = '';

  deviceFiltered = this.device.slice(0);

  selectFiltered(){
    this.deviceFiltered.forEach(i=>i.checked=true);
  }

  deSelectFiltered(){
    this.deviceFiltered.forEach(i=>i.checked=false);
  }

  onFilterChange(){
    if (this.deviceFilter.length > 0) {
      this.deviceFiltered = this.device.filter(i => i.name.indexOf(this.deviceFilter) > -1);
      console.log(this.deviceFiltered);
    } else {
      this.deviceFiltered = this.device.slice(0);
    }
  }
}

app.component.html

<h2><a [href]="titleUrl">{{title}}</a></h2>

<div>
  Filter
  <input [(ngModel)]="deviceFilter" (ngModelChange)="onFilterChange()">
</div>

<div>
  List:
  <ul>
    <li *ngFor="let i of device">
      <input type="checkbox" [(ngModel)]="i.checked">{{i.name}}
    </li>
  </ul>
</div>

<div>
  Filtered List:
  <ul>
    <li *ngFor="let i of deviceFiltered">
      <input type="checkbox" [(ngModel)]="i.checked">{{i.name}}
    </li>
  </ul>
  <button (click)="selectFiltered()">Select Filtered</button>
  <button (click)="deSelectFiltered()">Deselect Filtered</button>
</div>