Question

我有一个设计，我通过从下拉列表中选择一个项目来向我的页面添加芯片。我可以点击它来删除芯片。但是，我似乎无法清除select元素的值。我尝试了几件事，但没有一件能奏效。

使用Angular Material选择元素： https://plnkr.co/edit/KU1CxBqLwG5XtbvyEjJj?p=preview

使用Angular select元素： https://plnkr.co/edit/ewSlIRDHii3PnXRtnKgw?p=preview

HTML：

<div class="chips-overview-example">
  <md-card>
    <md-toolbar color="primary">Dynamic Chips</md-toolbar>
    <md-card-content>
      <md-chip-list>
        <md-chip *ngFor="let person of people" (click)="remove($event)">
          {{person.name}}
        </md-chip>

        <md-select id="names" 
                   placeholder="Names" 
                   [ngModel]="name"
                   (ngModelChange)="add($event)">
          <md-option *ngFor="let name of names" 
                     value="{{name.code}}">
            {{name.name}}
          </md-option>
        </md-select>
      </md-chip-list>
    </md-card-content>
  </md-card>
</div>

Component.ts

import {Component, ElementRef, Output} from '@angular/core';

export interface Person {
  name: string;
}

@Component({
  selector: 'chips-overview-example',
  templateUrl: 'chips-overview-example.html',
  styleUrls: ['chips-overview-example.css']
})
export class ChipsOverviewExample {
  visible: boolean = true;
  @Output() nameForm;

  names = [
    {code: "F",name: "Frank",description: ""},
    {code: "G",name: "George",description: ""},
    {code: "H",name: "Henry",description: ""},
    {code: "I",name: "Inigo",description: ""},
    {code: "J",name: "Jose",description: ""},
    {code: "K",name: "Kevin",description: ""}
  ];

  removedNames = [];

  people: Person[] = [];

  add(selection): void {
    let selected = this.names.find(el => el.code === selection);
    console.log("adding: ", selected, " to ", JSON.stringify(this.people));

    this.people.push({name: selected.name});

    this.removedNames.push(selected);
    this.names.splice(this.names.findIndex(el => el === selected), 1);
  }

  remove(chip) {
    let name = chip.target.innerText;
    let index = this.people.findIndex(el => el.name === name);
    this.people.splice(index, 1);
    this.names.push(this.removedNames.find(el => el.name === name));
    this.removedNames.splice(this.removedNames.findIndex(el => el.name === name), 1);
    this.names.sort(function(a, b) {
      if (a.name < b.name) return -1;
      if (a.name > b.name) return 1;
      return 0;
    });
  }



  toggleVisible(): void {
    this.visible = false;
  }
}

main.ts（模块）

import {platformBrowserDynamic} from '@angular/platform-browser-dynamic';
import {BrowserModule} from '@angular/platform-browser';
import {NgModule} from '@angular/core';
import {FormsModule, ReactiveFormsModule} from '@angular/forms';
import {MaterialModule} from '@angular/material';
import {ChipsOverviewExample} from './chips-overview-example';

@NgModule({

  imports: [
    BrowserModule,
    FormsModule,
    ReactiveFormsModule,
    MaterialModule,
  ],

  declarations: [ChipsOverviewExample],
  bootstrap: [ChipsOverviewExample],
  providers: []
})
export class PlunkerAppModule {}

platformBrowserDynamic().bootstrapModule(PlunkerAppModule);

Answer 1

我通过添加功能“修复”了这个问题。在添加芯片的过程中，我还从下拉列表中删除了值。用户无法再选择它，系统也不能选择它。

不幸的是，当我删除芯片时，我将该选项添加回下拉列表。如果该选项是最后一个选项，它将显示在输入框中。

不完整（傻瓜）证明。

无论如何，这里是更新add（）和remove（）方法。

x -= ...

最后的答案是使用formGroup上的patchValue方法直接修改值。 https://angular.io/docs/ts/latest/guide/reactive-forms.html#!#set-data

如何清除选择元素

1 个答案: