Angular 提供了两种不同的方法来通过表单处理用户输入:响应式表单和模板驱动表单。 本节先讲响应式表单。 最终实例demo (opens new window) app-component.ts
import { Component } from '@angular/core';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';
import { Observable } from 'rxjs';
import { tap } from 'rxjs/operators';
import { UserService, User } from './user.service';
@Component({
selector: 'my-app',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
form: FormGroup;
user$: Observable<User>;
constructor(
private formBuilder: FormBuilder,
private userService: UserService) { }
ngOnInit() {
this.form = this.formBuilder.group({
firstName: ['Jack', Validators.required],
lastName: ['Jones', Validators.required],
about: []
});
}
submit() {
if (this.form.valid) {
console.log(this.form.value);
}
}
}
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app-component.html
<form [formGroup]="form" (ngSubmit)="submit()">
<label for="firstname">First Name</label>
<input id="firstname" formControlName="firstName" />
<div *ngIf="form.controls.firstName.errors?.required && form.controls.firstName.touched" class="error">
*Required
</div>
<label for="lastname">Last Name</label>
<input id="lastname" formControlName="lastName" />
<div *ngIf="form.controls.lastName.errors?.required && form.controls.lastName.touched" class="error">
*Required
</div>
<label for="about">About</label>
<textarea id="about" formControlName="about"></textarea>
<button [disabled]="!form.valid">Save Profile</button>
</form>
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# 需要注意的几点:
- 使用响应式表单,需要组件所在的module引入ReactiveFormsModule (opens new window) 该module提供了很多指令。比如已Accessor结尾的,如
NumberValueAccessor
是专门处理,RadioControlValueAccessor
处理 等等。 - 模板中表单元素需要绑定FormControlName属性与TS中定义的FormControl匹配。 TS中的定义表单可以使用FormControl,如果嫌麻烦,有更简便的FormBuilder.group
this.personForm = this.formBuilder.group({
username: ['', Validators.required],
email: ['', [Validators.required, Validators.email]],
age: ['', Validators.required],
...
});
// 也可以写成
this.personForm = new FormGroup({
username: new FormControl('', Validators.required),
email: new FormControl('', Validators.required),
});
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- 表单元素上面不要同时出现formControlName和ngModel
如
<input formControlName="first" [(ngModel)]="value">
。使用formControlName
实际已经隐含绑定了ngModel。