嗨,我正试图创建一个角度指令来比较密码和确认密码。我尝试了网上展示的许多示例,但似乎都不起作用,在验证函数中,@input值总是未定义的,哪里会出错
以下是我的模板代码
<div>
<h1>Add user</h1>
<form #f="ngForm" novalidate>
<div>
<label>Password</label>
<input type="password" name="password" [ngModel]="user.password"
required #password="ngModel">
<small [hidden]="password.valid || (password.pristine &&
!f.submitted)">
Password is required
</small>
</div>
<div>
<label>Retype password</label>
<input type="password" name="confirmPassword"
[ngModel]="user.confirmPassword"
required compare="password" #confirmPassword="ngModel">
<small [hidden]="confirmPassword.valid ||
(confirmPassword.pristine && !f.submitted)">
Password mismatch
</small>
</div>
</form>
</div>
指令代码如下
import { Directive, Input, OnInit } from '@angular/core';
import {NG_VALIDATORS,AbstractControl,ValidationErrors,Validator} from '@angular/forms'
@Directive({
selector: '[compare]',
providers:[{provide:NG_VALIDATORS,useClass:ValidateEqualDirective,multi:true}]
})
export class ValidateEqualDirective implements Validator,OnInit {
@Input('compare') controlToCompare;
public controlCompate
constructor() { }
ngOnInit(){
console.log(this.controlToCompare)
}
validate(val:AbstractControl):ValidationErrors|null{
console.log(this.controlToCompare);
return null;
}
}
它打印未定义,因为您告诉Angular通过useClass
:为验证器创建一个新的ValidateEqualDirective实例
providers:[{provide:NG_VALIDATORS, useClass:ValidateEqualDirective
^^^^
这意味着您有两个类实例:第一个绑定到html结构,第二个创建用于验证。
您应该使用相同的指令实例:
providers:[{provide:NG_VALIDATORS, useExisting: ValidateEqualDirective
^^^^^^^^^^^^^^^
reuse current directive instance