Question

我有一个子组件如下，

Child component.html

 <div >
        <button type="button" data-toggle="dropdown" aria-haspopup="true" (click)="toggleDropdown()">
            {{ slectedItemName }} <span ></span>
        </button>
        <div *ngIf="showDropdown>
            <ul class="default-dropdown">
                <li *ngFor="let item of list" (click)="onSelectItem(item.value)" [ngClass]="{'active': item.value==selected}">
                    <a>{{item.name}}</a>
                </li>
            </ul>
        </div>
    </div>

Child component.ts

import { Component, Input, Output, EventEmitter } from '@angular/core';
declare const _: any;
@Component({
  moduleId: module.id,
  selector: 'dropdown',
  templateUrl: 'dropdown.component.html'
})
export class DropdownComponent {
  @Input() list: any;
  @Input() selected: string;
  @Output() onSelect = new EventEmitter<any>();
  showDropdown: boolean;
  slectedItemName: string;
  constructor() {
    this.showDropdown = false;
  }
  ngOnInit() {
    this.setSelected(this.selected);
  }
  setSelected(selected: string) {
    const selectedItem = _.find(this.list, (item: any) => {
      return item.value === selected;
    });
    this.slectedItemName = selectedItem.name;
  }
  toggleDropdown() {
    this.showDropdown = !this.showDropdown;
  }
  onSelectItem(selected: string) {
    this.onSelect.emit(selected);
    this.setSelected(selected);
    this.toggleDropdown();
  }
}

我在父组件中使用此子组件，如下所示，

  <div class="col-md-offset-2 col-md-8 search-filter-buttongroup-wrapper">
                <ul>
                    <li class="timeframe">
                        <dropdown [list]="allRegions" [selected]="selectedRegion" (onSelect)="onSelectRegion($event)">
                        </dropdown>
                    </li> 
                    <li class="clear-text header-search-block-text" (click)="clearFilters()">
                        <span><img src="../imgs/reset.svg">Clear Filters</span>
                    </li>
                </ul>
            </div>

当更改下拉列值设置正确时，单击清除过滤器时我将重置值。但是值的变化没有反映在父组件上。它仍然显示选定的值。这是清除所选值的功能。

  clearFilters() {    
    this.selectedRegion = '';
  }

问题是什么？

Answer 1

您没有更新selectedItemName 使用此代替@Input()selected:string：

  selected:string;
  @Input("selected") 
  set _selected(selected: string){
    this.selected = selected;
    if(this.list){
      const selectedItem = _.find(this.list, (item: any) => {
        return item.value === selected;
      });
      this.slectedItemName = selectedItem.name;
    }
  }

重置值时，组件不会被清除

1 个答案: