我试图实现自定义验证器。非异步的那个 (cannotContainSpaces) 运行得很好。而异步的那个 (shouldBeUnique)，目前来说确实很琐碎，但是我理解应该返回 Promise，然后 Validator 对象应该会解析它。但事实并非如此。在控制台中，username 的 FormControl 表单控件中的错误集合显示了这一点：
{__zone_symbol__state: null, __zone_symbol__value: Array(0)}
表单组件:
import { CustomValidators } from './custom.validators';
import { Component, Input } from '@angular/core';
import { FormGroup, FormControl, Validators } from '@angular/forms';
@Component({
selector: 'signup-form',
templateUrl: './signup-form.component.html',
styleUrls: ['./signup-form.component.css']
})
export class SignupFormComponent {
form = new FormGroup({
username: new FormControl('', [
CustomValidators.cannotContainSpaces,
CustomValidators.shouldBeUnique
// Validators.email,
]),
password: new FormControl('', Validators.required)
})
get username() {
return this.form.get('username');
}
keyPressed(){
console.log(this.username.errors)
}
}
自定义验证器方法：
import { AbstractControl, ValidationErrors } from "@angular/forms";
export class CustomValidators {
static cannotContainSpaces(control: AbstractControl) : ValidationErrors | null {
if ((<string>control.value).indexOf(' ') >= 0)
return { cannotContainSpaces: true};
return null;
}
static shouldBeUnique(control: AbstractControl) : Promise<ValidationErrors | null> {
return new Promise((resolve, reject) => {
setTimeout(function() {
if (control.value === 'treve')
resolve({shouldBeUnique: true});
else resolve(null);
}, 2000);
});
}
}
相关的HTML：
<form [formGroup]="form">
<div class="form-group">
<label for="username">Username</label>
<input
(keyup) = "keyPressed()" (blur) = "keyPressed()"
formControlName="username"
id="username"
type="text"
class="form-control">
<div *ngIf="username.touched && username.invalid" class="alert alert-danger">
<div *ngIf="username.errors.cannotContainSpaces">Username must not contain spaces</div>
<div *ngIf="username.errors.shouldBeUnique">Sorry, that username has been taken</div>
</div>
</div>