Angular表单验证分为两种验证：1.内置验证（required，minlength等）；2.自定义验证（正则表达式）。

接下来我们用一个注册账号的demo来看一下这两种验证是如何实现的。

项目界面

一、内置验证

其中账户名有required验证和最短长度验证，其他两个只有required验证

1.项目目录

----------app.component.ts

----------app.component.html

----------app.component.css

----------app.module.ts

2.项目代码

app.module.ts

import { BrowserModule } from '@angular/platform-browser';import { NgModule } from '@angular/core';import { FormsModule,ReactiveFormsModule } from '@angular/forms';//表单验证必须导入这两个模块import { AppComponent } from './app.component';@NgModule({ declarations: [ AppComponent ], imports: [ BrowserModule, FormsModule, //注册模块 ReactiveFormsModule ], providers: [], bootstrap: [AppComponent]})export class AppModule { }

app.component.ts

import { Component,OnInit } from '@angular/core';import { FormGroup, FormControl, Validators } from '@angular/forms';@Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css']})export class AppComponent { title = 'app'; Form:FormGroup; data={ name:"", email:"", tel:"" } ngOnInit(): void { this.Form = new FormGroup({ 'name': new FormControl(this.data.name, [ Validators.required, Validators.minLength(4) ]), 'email': new FormControl(this.data.email, Validators.required), 'tel': new FormControl(this.data.tel, Validators.required) }); } get name() { return this.Form.get('name'); } get email() { return this.Form.get('email'); } get tel() { return this.Form.get('tel'); }}

简单来说，在使用验证表单的时候，大致分为四步：

（1）导入相关模块FormGroup, FormControl, Validators；

（2）声明表单验证变量From:FromGroup；

（3）定义验证规则；

（4）通过它所属的控件组（FormGroup）的get方法来访问表单控件

app.component.html

<div class="wrapper"> <div class="row"> <p class="title-wrapper">注册账号</p> </div> <div class="row"> <div class="contain-wrapper" [formGroup]="Form"> <label for="name">账户名：</label> <input type="text" id="name" formControlName="name"><br/> <div *ngIf="name.invalid && (name.dirty || name.touched)" class="alert alert-danger"> <div *ngIf="name.errors.required"> 请输入长度账户名！ </div> <div *ngIf="name.errors.minlength"> 账户名长度不小于4！ </div> </div> <label for="email">邮箱：</label> <input type="text" id="email" formControlName="email"><br/> <div *ngIf="email.invalid && (email.dirty || email.touched)" class="alert alert-danger"> <div *ngIf="email.errors.required"> 请输入邮箱！ </div> </div> <label for="tel">电话:</label> <input type="text" id="tel" formControlName="tel"> <div *ngIf="tel.invalid && (tel.dirty || tel.touched)" class="alert alert-danger"> <div *ngIf="tel.errors.required"> 请输入电话！ </div> </div> </div> </div> <div class="row"> <button class="btn btn-primary confirm">确认</button> </div></div>

app.component.css

*{ font-size: 18px;}.wrapper{ margin: 0 auto; margin-top:10%; width:30%; height: 20%; border:1px solid black; border-radius: 10px;}.title-wrapper{ margin: 0 auto; padding-top: 20px; padding-bottom: 20px; width:370px; text-align: center; font-size: 20px; font-weight: 800;}label{ display: inline-block; width:72px;}.contain-wrapper{ width: 300px; margin:0 auto;}.confirm{ margin-top:20px; width:100%;}

3.项目效果

二、自定义验证

自定义表单验证，需要创建自定义验证器，我们接下来更改邮箱的验证，将其改为有格式的验证，而不是单纯的存在验证，首先我们来看一下项目目录的更改

1.项目目录

----------app.component.ts

----------app.component.html

----------app.component.css

----------app.module.ts

----------emailAuthentication.ts

2.项目代码

app.module.ts

注册自定义验证器EmailValidatorDirective

import { BrowserModule } from '@angular/platform-browser';import { NgModule } from '@angular/core';import { FormsModule,ReactiveFormsModule } from '@angular/forms';import { EmailValidatorDirective } from './emailAuthentication';import { AppComponent } from './app.component';@NgModule({ declarations: [ AppComponent, EmailValidatorDirective ], imports: [ BrowserModule, FormsModule, ReactiveFormsModule ], providers: [], bootstrap: [AppComponent]})export class AppModule { }

emailAuthentication.ts

import { Directive, Input, OnChanges, SimpleChanges } from '@angular/core';import { AbstractControl, NG_VALIDATORS, Validator, ValidatorFn, Validators } from '@angular/forms';/** A hero's name can't match the given regular expression */export function emailValidator(nameRe: RegExp): ValidatorFn { return (control: AbstractControl): { [key: string]: any } => { const forbidden = !nameRe.test(control.value); return forbidden ? { 'forbiddenName': { value: control.value } } : null; };}@Directive({ selector: '[appForbiddenName]', providers: [{ provide: NG_VALIDATORS, useExisting: EmailValidatorDirective, multi: true }]})export class EmailValidatorDirective implements Validator { @Input() forbiddenName: string; validate(control: AbstractControl): { [key: string]: any } { return this.forbiddenName ? emailValidator(new RegExp(this.forbiddenName, 'i'))(control) : null; }}

app.component.ts

import { Component,OnInit } from '@angular/core';import { FormGroup, FormControl, Validators } from '@angular/forms';import { emailValidator } from './emailAuthentication'; //导入emailValidator自定义验证器@Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css']})export class AppComponent { title = 'app'; //email的正则表达式 emailExp = /^([a-zA-Z0-9_-])+@([a-zA-Z0-9_-])+(.[a-zA-Z0-9_-])+/ ; Form:FormGroup; data={ name:"", email:"", tel:"" } ngOnInit(): void { this.Form = new FormGroup({ 'name': new FormControl(this.data.name, [ Validators.required, Validators.minLength(4) ]), 'email': new FormControl(this.data.email, [ Validators.required, emailValidator(this.emailExp) //自定义验证器 ]), 'tel': new FormControl(this.data.tel, Validators.required) }); } get name() { return this.Form.get('name'); } get email() { return this.Form.get('email'); } get tel() { return this.Form.get('tel'); }}

app.component.html

<div class="wrapper"> <div class="row"> <p class="title-wrapper">注册账号</p> </div> <div class="row"> <div class="contain-wrapper" [formGroup]="Form"> <label for="name">账户名：</label> <input type="text" id="name" formControlName="name"><br/> <div *ngIf="name.invalid && (name.dirty || name.touched)" class="alert alert-danger"> <div *ngIf="name.errors.required"> 请输入账户名！ </div> <div *ngIf="name.errors.minlength"> 账户名长度不小于4！ </div> </div> <label for="email">邮箱：</label> <input type="text" id="email" formControlName="email" required><br/> <div *ngIf="email.invalid && (email.dirty || email.touched)" class="alert alert-danger"> <div *ngIf="email.errors.forbiddenName"> 请输入正确格式的邮箱！ </div> </div> <label for="tel">电话:</label> <input type="text" id="tel" formControlName="tel"> <div *ngIf="tel.invalid && (tel.dirty || tel.touched)" class="alert alert-danger"> <div *ngIf="tel.errors.required"> 请输入电话！ </div> </div> </div> </div> <div class="row"> <button class="btn btn-primary confirm" [disabled]="Form.invalid" >确认</button> </div></div>

在最后确认的时候，我们设置一下按钮的disabled属性，在表单验证不通过的时候，确认按钮是点击不了的，显示不可点击状态。[disabled]="Form.invalid"。

3.项目效果

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