Angular实现表单验证功能

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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