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》】
1.1 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
1）、引入依赖模块 FormsModule
import { FormsModule } from "@angular/forms"
@NgModule({
imports: [FormsModule],
})
export class AppModule {}2）、将 DOM 表单转换为 ngForm
<form #f="ngForm" (submit)="onSubmit(f)"></form>
3）、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>
4）、获取表单字段值
import { NgForm } from "@angular/forms"
export class AppComponent {
onSubmit(form: NgForm) {
console.log(form.value) // {username: ''}
}
}5）、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>import { NgForm } from "@angular/forms"
export class AppComponent {
onSubmit(form: NgForm) {
console.log(form.value) // {contact: {phone: ''}, user:{username: ''}}
}
}1.3 表单验证
<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;
}2.1 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
1）、引入 ReactiveFormsModule
import { ReactiveFormsModule } from "@angular/forms"
@NgModule({
imports: [ReactiveFormsModule]
})
export class AppModule {}2）、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()
})
}3）、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>
4）、获取表单值
export class AppComponent {
onSubmit() {
console.log(this.contactForm.value)
}
}5）、设置表单默认值
contactForm: FormGroup = new FormGroup({
name: new FormControl("默认值"),
phone: new FormControl(15888888888)
})6）、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
1）、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)
])
})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>
3）、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"
import { Observable } from "rxjs"
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。
import { FormBuilder, FormGroup, Validators } from "@angular/forms"
export class AppComponent {
contactForm: FormGroup
constructor(private fb: FormBuilder) {
this.contactForm = this.fb.group({
fullName: this.fb.group({
firstName: ["", [Validators.required]],
lastName: [""]
}),
phone: []
})
}
}2.8 监听表单值的变化
实际工作中，我们常常需要根据某个表单值得变化而进行相应的处理，一般可以使用ngModalChange或者表单来实现
2.8.1 ngModalChange
<div> <input type="text" [(ngModal)]="name" (ngModalChange)="nameChange()" /> </div>
import { FormControl, FormGroup } from "@angular/forms"
export class AppComponent {
public name = 'a';
public nameChange() {
}
}angular官方并不建议使用ngModalChange。
2.8.2 表单控制
<div [formGroup]="contactForm"> <input type="text" formControlName="name" /> </div>
import { FormControl, FormGroup } from "@angular/forms"
export class AppComponent {
contactForm: FormGroup = new FormGroup({
name: new FormControl()
})
ngOnInt() {
this.contactForm.get("name").valueChanges.subscribe(data => {
console.log(data);
}
}
}2.9 练习
1）、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)
}
}2）、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>
2.10 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