Angular2中的选择事件
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【中文标题】Angular2中的选择事件【英文标题】:Selects' events in Angular2 【发布时间】:2015-09-19 14:15:26 【问题描述】:拜托,你能帮帮我吗?这应该很容易,但我找不到解决方案。有一个带有两个选择的表单。当#select1 发生变化时,#select2 需要根据#select1 的值显示数据。例如,获取每个州的城市。种类:
//html
<select (change)="select2.getCities($event)" ng-control="userState">
<option *ng-for="#state of states" [value]="state">state</option>
</select>
<select #select2 ng-control="userCity">
<option *ng-for="#city of cities" [value]="city">city</option>
</select>
//the Component
@Component( selector: 'user-management', appInjector: [FormBuilder] );
@View( templateUrl: 'user-management.html', directives: [NgFor] );
export class userManagement
constructor(fb: FormBuilder)
this.userForm = fb.group(
userState: [],
userCity: []
);
this.states = ['New York', 'Pennsylvania'];
this.cities = 'New York': ['Albany', 'Buffalo'], 'Pennsylvania':['Pittsburgh', 'Philadelphia'];
getCities($event)
return this.cities[$event.target.value];
这当然行不通。请问,你知道应该怎么做吗?它在 alpha28 中。
【问题讨论】:
【参考方案1】:太棒了!我发现了如何让它工作! :) 唯一缺少的是传递给事件的表单模型。应该是这样的:
<form [ng-form-model]="userForm">
<select (change)="select2.getCities($event, userForm)" ng-control="userState">
<option *ng-for="#state of states" [value]="state">state</option>
</select>
【讨论】:
【参考方案2】:用 Angular 2 最新的template syntax 和 Typescript 组件回答
//The Component Type script
import Component from 'angular2/core';
import NgForm from 'angular2/common';
@Component( selector: 'states-cities',
template: `
<form (ngSubmit)="onSubmit()" #heroForm="ngForm">
<select ngControl="state" #state="ngForm" (change)="getCities(state)">
<option *ngFor="#state of states" [value]="state" >state</option>
</select>
<select ngControl="userCity" #select2="ngForm">
<option *ngFor="#city of cities" [value]="city">city</option>
</select>
</form>
`
)
export class stateCitiesComponent
states= ['New York', 'Pennsylvania'];
cities = [];
citiesData='New York': ['Albany', 'Buffalo'], 'Pennsylvania':['Pittsburgh', 'Philadelphia'];
getCities(state)
this.cities=this.citiesData[state.value];
【讨论】:
【参考方案3】:这就是我在 Angular 2 RC5 上使用模型驱动方法和 Observables 的方式。这也可以是一个搜索字段,然后您可以在其中使用 debounceTime()
来避免每次击键时都点击您的后端或进一步操作输入。
//The Component Type script
import Component from '@angular/core';
import FormControl, FormGroup, FormBuilder from '@angular/forms';
@Component(
moduleId: module.id,
selector: 'states-cities',
template: `
<form [formGroup]="myForm" (ngSubmit)="onSubmit()">
<select formControlName="state">
<option *ngFor="let state of states" [value]="state" >state</option>
</select>
<select formControlName="userCity">
<option *ngFor="let city of cities" [value]="city">city</option>
</select>
</form>
`
)
export class stateCitiesComponent
states:Array<string>;
cities:Array<string>;
citiesData:any;
myForm:FormGroup;
constructor(private formBuilder: FormBuilder)
this.states = ['New York', 'Pennsylvania'];
this.cities = [];
this.citiesData = 'New York': ['Albany', 'Buffalo'], 'Pennsylvania':['Pittsburgh', 'Philadelphia'];
// Setup Form
this.myForm = this.formBuilder.group(
state: [''],
userCity: ['']
);
// Now setup change detection with an Observable
this.myForm.controls["state"].valueChanges
.debounceTime(100) // wait a litle after the user input (ms)
.subscribe(state =>
this.cities = this.citiesData[state];
);
onSubmit()
// do something
您可以阅读more about change detection here。
【讨论】:
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