所属分类:web前端开发
在 Angular
中,表单有两种类型,分别为模板驱动和模型驱动。【相关教程推荐:《angular教程》】
1. 模板驱动
1.1 概述
表单的控制逻辑写在组件模板中,适合简单的表单类型
1.2 快速上手
引入依赖模块 FormsModule
import { FormsModule } from "@angular/forms" @NgModule({ imports: [FormsModule], }) export class AppModule {}
将 DOM
表单转换为 ngForm
<form #f="ngForm" (submit)="onSubmit(f)"></form>
声明表单字段为 ngModel
<form #f="ngForm" (submit)="onSubmit(f)"> <input type="text" name="username" ngModel /> <button>提交</button> </form>
获取表单字段值
import { NgForm } from "@angular/forms" export class AppComponent { onSubmit(form: NgForm) { console.log(form.value) } }
表单分组
<form #f="ngForm" (submit)="onSubmit(f)"> <div ngModelGroup="user"> <input type="text" name="username" ngModel /> </div> <div ngModelGroup="contact"> <input type="text" name="phone" ngModel /> </div> <button>提交</button> </form>
1.3 表单验证
required
必填字段minlength
字段最小长度maxlength
字段最大长度pattern
验证正则 例如:pattern="\d"
匹配一个数值<form #f="ngForm" (submit)="onSubmit(f)"> <input type="text" name="username" ngModel required pattern="\d" /> <button>提交</button> </form>
export class AppComponent { onSubmit(form: NgForm) { // 查看表单整体是否验证通过 console.log(form.valid) } }
<!-- 表单整体未通过验证时禁用提交表单 --> <button type="submit" [disabled]="f.invalid">提交</button>
在组件模板中显示表单项未通过时的错误信息
<form #f="ngForm" (submit)="onSubmit(f)"> <input #username="ngModel" /> <div *ngIf="username.touched && !username.valid && username.errors"> <div *ngIf="username.errors.required">请填写用户名</div> <div *ngIf="username.errors.pattern">不符合正则规则</div> </div> </form>
指定表单项未通过验证时的样式
input.ng-touched.ng-invalid { border: 2px solid red; }
2. 模型驱动
2.1 概述
表单的控制逻辑写在组件类中,对验证逻辑拥有更多的控制权,适合复杂的表单的类型。
在模型驱动表单中,表单字段需要是 FormControl
类的实例,实例对象可以验证表单字段中的值,值是否被修改过等等
一组表单字段构成整个表单,整个表单需要是 FormGroup
类的实例,它可以对表单进行整体验证
FormControl
:表单组中的一个表单项
FormGroup
:表单组,表单至少是一个 FormGroup
FormArray
:用于复杂表单,可以动态添加表单项或表单组,在表单验证时,FormArray
中有一项没通过,整体没通过
2.2 快速上手
引入 ReactiveFormsModule
import { ReactiveFormsModule } from "@angular/forms" @NgModule({ imports: [ReactiveFormsModule] }) export class AppModule {}
在组件类中创建 FormGroup
表单控制对象
import { FormControl, FormGroup } from "@angular/forms" export class AppComponent { contactForm: FormGroup = new FormGroup({ name: new FormControl(), phone: new FormControl() }) }
关联组件模板中的表单
<form [formGroup]="contactForm" (submit)="onSubmit()"> <input type="text" formControlName="name" /> <input type="text" formControlName="phone" /> <button>提交</button> </form>
获取表单值
export class AppComponent { onSubmit() { console.log(this.contactForm.value) } }
设置表单默认值
contactForm: FormGroup = new FormGroup({ name: new FormControl("默认值"), phone: new FormControl(15888888888) })
表单分组
contactForm: FormGroup = new FormGroup({ fullName: new FormGroup({ firstName: new FormControl(), lastName: new FormControl() }), phone: new FormControl() })
<form [formGroup]="contactForm" (submit)="onSubmit()"> <div formGroupName="fullName"> <input type="text" formControlName="firstName" /> <input type="text" formControlName="lastName" /> </div> <input type="text" formControlName="phone" /> <button>提交</button> </form>
onSubmit() { console.log(this.contactForm.value.name.username) console.log(this.contactForm.get(["name", "username"])?.value) }
2.3 FormArray
需求:在页面中默认显示一组联系方式,通过点击按钮可以添加更多联系方式组
import { Component, OnInit } from "@angular/core" import { FormArray, FormControl, FormGroup } from "@angular/forms" @Component({ selector: "app-root", templateUrl: "./app.component.html", styles: [] }) export class AppComponent implements OnInit { // 表单 contactForm: FormGroup = new FormGroup({ contacts: new FormArray([]) }) get contacts() { return this.contactForm.get("contacts") as FormArray } // 添加联系方式 addContact() { // 联系方式 const myContact: FormGroup = new FormGroup({ name: new FormControl(), address: new FormControl(), phone: new FormControl() }) // 向联系方式数组中添加联系方式 this.contacts.push(myContact) } // 删除联系方式 removeContact(i: number) { this.contacts.removeAt(i) } ngOnInit() { // 添加默认的联系方式 this.addContact() } onSubmit() { console.log(this.contactForm.value) } }
<form [formGroup]="contactForm" (submit)="onSubmit()"> <div formArrayName="contacts"> <div *ngFor="let contact of contacts.controls; let i = index" [formGroupName]="i" > <input type="text" formControlName="name" /> <input type="text" formControlName="address" /> <input type="text" formControlName="phone" /> <button (click)="removeContact(i)">删除联系方式</button> </div> </div> <button (click)="addContact()">添加联系方式</button> <button>提交</button> </form>
2.4 内置表单验证器
使用内置验证器提供的验证规则验证表单字段
import { FormControl, FormGroup, Validators } from "@angular/forms" contactForm: FormGroup = new FormGroup({ name: new FormControl("默认值", [ Validators.required, Validators.minLength(2) ]) })
获取整体表单是否验证通过
onSubmit() { console.log(this.contactForm.valid) }
<!-- 表单整体未验证通过时禁用表单按钮 --> <button [disabled]="contactForm.invalid">提交</button>
在组件模板中显示为验证通过时的错误信息
get name() { return this.contactForm.get("name")! }
<form [formGroup]="contactForm" (submit)="onSubmit()"> <input type="text" formControlName="name" /> <div *ngIf="name.touched && name.invalid && name.errors"> <div *ngIf="name.errors.required">请填写姓名</div> <div *ngIf="name.errors.maxlength"> 姓名长度不能大于 {{ name.errors.maxlength.requiredLength }} 实际填写长度为 {{ name.errors.maxlength.actualLength }} </div> </div> </form>
2.5 自定义同步表单验证器
自定义验证器的类型是 TypeScript
类
类中包含具体的验证方法,验证方法必须为静态方法
验证方法有一个参数 control
,类型为 AbstractControl
。其实就是 FormControl
类的实例对象的类型
如果验证成功,返回 null
如果验证失败,返回对象,对象中的属性即为验证标识,值为 true
,标识该项验证失败
验证方法的返回值为 ValidationErrors | null
import { AbstractControl, ValidationErrors } from "@angular/forms" export class NameValidators { // 字段值中不能包含空格 static cannotContainSpace(control: AbstractControl): ValidationErrors | null { // 验证未通过 if (/\s/.test(control.value)) return { cannotContainSpace: true } // 验证通过 return null } }
import { NameValidators } from "./Name.validators" contactForm: FormGroup = new FormGroup({ name: new FormControl("", [ Validators.required, NameValidators.cannotContainSpace ]) })
<div *ngIf="name.touched && name.invalid && name.errors"> <div *ngIf="name.errors.cannotContainSpace">姓名中不能包含空格</div> </div>
2.6 自定义异步表单验证器
import { AbstractControl, ValidationErrors } from "@angular/forms" export class NameValidators { static shouldBeUnique(control: AbstractControl): Promise<ValidationErrors | null> { return new Promise(resolve => { if (control.value == "admin") { resolve({ shouldBeUnique: true }) } else { resolve(null) } }) } }
contactForm: FormGroup = new FormGroup({ name: new FormControl( "", [ Validators.required ], NameValidators.shouldBeUnique ) })
<div *ngIf="name.touched && name.invalid && name.errors"> <div *ngIf="name.errors.shouldBeUnique">用户名重复</div> </div> <div *ngIf="name.pending">正在检测姓名是否重复</div>
2.7 FormBuilder
创建表单的快捷方式。
this.fb.control
:表单项
this.fb.group
:表单组,表单至少是一个 FormGroup
this.fb.array
:用于复杂表单,可以动态添加表单项或表单组,在表单验证时,FormArray
中有一项没通过,整体没通过
2.8 练习
获取一组复选框中选中的值
<form [formGroup]="form" (submit)="onSubmit()"> <label *ngFor="let item of Data"> <input type="checkbox" [value]="item.value" (change)="onChange($event)" /> {{ item.name }} </label> <button>提交</button> </form>
import { Component } from "@angular/core" import { FormArray, FormBuilder, FormGroup } from "@angular/forms" interface Data { name: string value: string } @Component({ selector: "app-checkbox", templateUrl: "./checkbox.component.html", styles: [] }) export class CheckboxComponent { Data: Array<Data> = [ { name: "Pear", value: "pear" }, { name: "Plum", value: "plum" }, { name: "Kiwi", value: "kiwi" }, { name: "Apple", value: "apple" }, { name: "Lime", value: "lime" } ] form: FormGroup constructor(private fb: FormBuilder) { this.form = this.fb.group({ checkArray: this.fb.array([]) }) } onChange(event: Event) { const target = event.target as HTMLInputElement const checked = target.checked const value = target.value const checkArray = this.form.get("checkArray") as FormArray if (checked) { checkArray.push(this.fb.control(value)) } else { const index = checkArray.controls.findIndex( control => control.value === value ) checkArray.removeAt(index) } } onSubmit() { console.log(this.form.value) } }
获取单选框中选中的值
export class AppComponent { form: FormGroup constructor(public fb: FormBuilder) { this.form = this.fb.group({ gender: "" }) } onSubmit() { console.log(this.form.value) } }
<form [formGroup]="form" (submit)="onSubmit()"> <input type="radio" value="male" formControlName="gender" /> Male <input type="radio" value="female" formControlName="gender" /> Female <button type="submit">Submit</button> </form>
2.9 其他
patchValue
:设置表单控件的值(可以设置全部,也可以设置其中某一个,其他不受影响)
setValue
:设置表单控件的值 (设置全部,不能排除任何一个)
valueChanges
:当表单控件的值发生变化时被触发的事件
reset
:表单内容置空
updateValueAndValidity
:对指定输入框 取消校验
validateForm: FormGroup; this.validateForm.get('cpwd').updateValueAndValidity();
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