浅析Angular中两种类型的Form表单
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): PRomiseValidationErrors | 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: ArrayData> = [ { 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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