我有一个选择列表,它使用[ngValue]绑定到组件上的Person属性。当我更改选择时,underyling selectedPerson属性将按预期更新。但是,如果我在代码中更改所选人员,则select在初始化时不会默认为所选人员。
对我所缺少的任何帮助都将不胜感激。这是我的代码......
import {Component, OnInit, NgModule} from '@angular/core'
import {BrowserModule} from '@angular/platform-browser'
import { FormsModule } from '@angular/forms';
@Component({
selector: 'my-app',
template: `
<form>
<select [(ngModel)]="selectedPerson"
name="selectedPerson">
<option [ngValue]="null">Please choose...</option>
<option *ngFor="let p of people"
[ngValue]="p"
[attr.selected]="p.personId === selectedPerson?.personId ? true : null ">{{p.name}}</option>
</select>
<p>The selected person is {{selectedPerson?.name}}</p>
<button type="button" (click)="selectJane()">Select Jane</button>
<button type="button" (click)="clearSelection()">Clear Selection</button>
</form>`,
})
export class App implements OnInit {
public ngOnInit() {
this.people = [
{ personId: 1, name: "Tom" },
{ personId: 2, name: "Mary" },
{ personId: 3, name: "Jane" }
]
this.selectedPerson = { personId: 2, name: "Mary" }
}
public people: Person[];
public selectedPerson: Person;
public selectJane(){
this.selectedPerson = { personId: 3, name: "Jane" }
}
public clearSelection(){
this.selectedPerson = null;
}
}
export class Person {
public personId: number;
public name: string;
}
@NgModule({
imports: [ BrowserModule, FormsModule ],
declarations: [ App ],
bootstrap: [ App ]
})
export class AppModule {}
...这里是一个Plunker http://plnkr.co/edit/ag94mZO9Zggg1kZx8jJV
答案 0 :(得分:7)
问题是,通过使用ngValue
,select
需要相同的引用,而不仅仅是类似的对象。
您可以添加一个方法来按名称选择:
public selectByName(name: string) {
this.selectedPerson = this.people.find(person => person.name === name);
}
然后在ngOnInit()
:
this.selectByName("Mary");
// or this.selectedPerson = this.people[2];
在selectJane()
:
public selectJane(){
this.selectByName("Jane");
}
您更新的Plunker