這篇文章帶大家了解一下Angular中兩種Form表單，簡單介紹一下它們的用法，希望對大家有幫助！
在 Angular 中，表單有兩種類型，分別為範本驅動和模型驅動。 【相關教學推薦：《angular教學》】
1. 模板驅動
##1.1 概述
表單的控制邏輯寫在元件範本中，適合簡單的表單類型
#1.2 快速上手
引入依賴模組
FormsModule
import { FormsModule } from "@angular/forms"
@NgModule({
imports: [FormsModule],
})
export class AppModule {}登入後複製
將
DOM 表單轉換為ngForm
<form #f="ngForm" (submit)="onSubmit(f)"></form>
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聲明表單欄位為
ngModel
<form #f="ngForm" (submit)="onSubmit(f)">
<input type="text" name="username" ngModel />
<button>提交</button>
</form>
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取得表單欄位值
import { NgForm } from "@angular/forms"
export class AppComponent {
onSubmit(form: NgForm) {
console.log(form.value)
}
}登入後複製
表單分組
<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>登入後複製
1.3 表單驗證
- required
#填欄位 - minlength
欄位最小長度 - #maxlength
欄位最大長度 - pattern
# 驗證正規例如：pattern="\d" 符合一個數值 <form #f="ngForm" (submit)="onSubmit(f)">
<input type="text" name="username" ngModel required pattern="\d" />
<button>提交</button>
</form>
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export class AppComponent {
onSubmit(form: NgForm) {
// 查看表单整体是否验证通过
console.log(form.valid)
}
}登入後複製
<!-- 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>
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在元件範本中顯示表單項目未通過時的錯誤訊息
<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>登入後複製
#指定表單項目未通過驗證時的樣式
input.ng-touched.ng-invalid {
border: 2px solid red;
}登入後複製
2. 模型驅動
2.1 概述
#表單的控制邏輯寫在元件類別中，對驗證邏輯擁有更多的控制權，適合複雜的表單的類型。
在模型驅動表單中，表單欄位需要是
FormControl 類別的實例，實例物件可以驗證表單欄位中的值，值是否被修改過等等
一組表單欄位構成整個表單，整個表單需要是
FormGroup 類別的實例，它可以對表單進行整體驗證
#2.2 快速上手
引入
ReactiveFormsModule
import { ReactiveFormsModule } from "@angular/forms"
@NgModule({
imports: [ReactiveFormsModule]
})
export class AppModule {}登入後複製
在元件類別中建立
FormGroup 表單控制物件
import { FormControl, FormGroup } from "@angular/forms"
export class AppComponent {
contactForm: FormGroup = new FormGroup({
name: new FormControl(),
phone: new FormControl()
})
}登入後複製
關聯元件範本中的表單
<form [formGroup]="contactForm" (submit)="onSubmit()">
<input type="text" formControlName="name" />
<input type="text" formControlName="phone" />
<button>提交</button>
</form>
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取得表單值
export class AppComponent {
onSubmit() {
console.log(this.contactForm.value)
}
}登入後複製
設定表單預設值
contactForm: FormGroup = new FormGroup({
name: new FormControl("默认值"),
phone: new FormControl(15888888888)
})登入後複製
表單分組
contactForm: FormGroup = new FormGroup({
fullName: new FormGroup({
firstName: new FormControl(),
lastName: new FormControl()
}),
phone: new FormControl()
})登入後複製
<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>登入後複製
onSubmit() {
console.log(this.contactForm.value.name.username)
console.log(this.contactForm.get(["name", "username"])?.value)
}登入後複製
2.3 FormArray
需求：在頁面中預設顯示一組聯絡方式，透過點擊按鈕可以新增更多聯絡方式群組
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)
}
}登入後複製
<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>登入後複製
2.4 內建表單驗證器##使用內建驗證器提供的驗證規則驗證表單欄位
import { FormControl, FormGroup, Validators } from "@angular/forms"
contactForm: FormGroup = new FormGroup({
name: new FormControl("默认值", [
Validators.required,
Validators.minLength(2)
])
})登入後複製
取得整體表單是否驗證透過
onSubmit() {
console.log(this.contactForm.valid)
}登入後複製
<!-- 表单整体未验证通过时禁用表单按钮 -->
<button [disabled]="contactForm.invalid">提交</button>
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在元件範本中顯示為驗證通過時的錯誤訊息
get name() {
return this.contactForm.get("name")!
}登入後複製
<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>登入後複製
2.5 自訂同步表單驗證器
2.6 自定義異步表單驗證器
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)
}
})
}
}登入後複製
contactForm: FormGroup = new FormGroup({
name: new FormControl(
"",
[
Validators.required
],
NameValidators.shouldBeUnique
)
})登入後複製
<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>
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2.7
FormBuilder
##2.8 練習
取得一組複選框中選取的值
<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>登入後複製
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)
}
}登入後複製
取得單選方塊中選取的值
export class AppComponent {
form: FormGroup
constructor(public fb: FormBuilder) {
this.form = this.fb.group({ gender: "" })
}
onSubmit() {
console.log(this.form.value)
}
}登入後複製
<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>
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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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