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淺析Angular19 自定義表單控件

來(lái)源：懂視網(wǎng) 責(zé)編：小采時(shí)間：2020-11-27 22:20:22

淺析Angular19 自定義表單控件

淺析Angular19 自定義表單控件:1 需求當(dāng)開(kāi)發(fā)者需要一個(gè)特定的表單控件時(shí)就需要自己開(kāi)發(fā)一個(gè)和默認(rèn)提供的表單控件用法相似的控件來(lái)作為表單控件；自定義的表單控件必須考慮模型和視圖之間的數(shù)據(jù)怎么進(jìn)行交互 2 官方文檔 -> 點(diǎn)擊前往 Angular為開(kāi)發(fā)者提供了ControlValueAcce

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點(diǎn)擊下載本文 文檔為doc格式

導(dǎo)讀淺析Angular19 自定義表單控件:1 需求當(dāng)開(kāi)發(fā)者需要一個(gè)特定的表單控件時(shí)就需要自己開(kāi)發(fā)一個(gè)和默認(rèn)提供的表單控件用法相似的控件來(lái)作為表單控件；自定義的表單控件必須考慮模型和視圖之間的數(shù)據(jù)怎么進(jìn)行交互 2 官方文檔 -> 點(diǎn)擊前往 Angular為開(kāi)發(fā)者提供了ControlValueAcce

1 需求

當(dāng)開(kāi)發(fā)者需要一個(gè)特定的表單控件時(shí)就需要自己開(kāi)發(fā)一個(gè)和默認(rèn)提供的表單控件用法相似的控件來(lái)作為表單控件；自定義的表單控件必須考慮模型和視圖之間的數(shù)據(jù)怎么進(jìn)行交互

2 官方文檔 -> 點(diǎn)擊前往

Angular為開(kāi)發(fā)者提供了ControlValueAccessor接口來(lái)輔助開(kāi)發(fā)者構(gòu)建自定義的表單控件，開(kāi)發(fā)者只需要在自定義表單控件類中實(shí)現(xiàn)ControlValueAccessor接口中的方法就可以實(shí)現(xiàn)模型和視圖之間的數(shù)據(jù)交互

interface ControlValueAccessor { 
 writeValue(obj: any): void
 registerOnChange(fn: any): void
 registerOnTouched(fn: any): void
 setDisabledState(isDisabled: boolean)?: void
}

2.1 writeValue

writeValue(obj: any): void

該方法用于將值寫(xiě)入到自定義表單控件中的元素；

這個(gè)參數(shù)值（obj）是使用這個(gè)自定義表單控件的組件通過(guò)模板表單或者響應(yīng)式表單的數(shù)據(jù)綁定傳過(guò)來(lái)的；

在自定義表單控件的類中只需要將這個(gè)值（obj）賦值給一個(gè)成員變量即可，自定義表單控件的視圖就會(huì)通過(guò)屬性綁定顯示出來(lái)這個(gè)值

2.2 registerOnChange

registerOnChange(fn: any): void

自定義表單控件的數(shù)據(jù)發(fā)生變化時(shí)會(huì)觸發(fā)registerOnChange方法，該方用于如何處理自定義表單控件數(shù)據(jù)的變化；

registerOnChange方法接收的參數(shù)（fn）其實(shí)是一個(gè)方法，該方法負(fù)責(zé)處理變化的數(shù)據(jù)

當(dāng)自定義控件數(shù)據(jù)變化時(shí)就會(huì)自動(dòng)調(diào)用fn執(zhí)行的方法，但是通常的做法是自定義一個(gè)方法 propagateChange 讓自定義的方法指向fn，這樣當(dāng)數(shù)據(jù)變化時(shí)只需要調(diào)用 propagateChange 就可以對(duì)變化的數(shù)據(jù)進(jìn)行處理

2.3 registerOnTouched

registerOnTouched(fn: any): void

表單控件被觸摸時(shí)會(huì)觸發(fā)registerOnTouched方法，具體細(xì)節(jié)待更新......2018-1-31 11:18:33

2.4 setDisabledState

setDisabledState(isDisabled: boolean)?: void

待更新......2018-1-31 11:19:30

3 編程步驟

3.1 創(chuàng)建自定義表單控件組件

<div>
 <h4>當(dāng)前計(jì)數(shù)為：{{countNumber}}</h4>
 <br />
 <div>
 <button md-icon-button (click)="onIncrease()">
 <span>增加</span>
 <md-icon>add</md-icon>
 </button>
 <span style="margin-left: 30px;"></span>
 <button md-icon-button (click)="onDecrease()">
 <span>減少</span>
 <md-icon>remove</md-icon>
 </button>
 </div>
</div>

HTML

import { Component, OnInit } from '@angular/core';
import { ControlValueAccessor } from '@angular/forms';
@Component({
 selector: 'app-counter',
 templateUrl: './counter.component.html',
 styleUrls: ['./counter.component.scss']
})
export class CounterComponent implements OnInit {
 countNumber: number = 0;
 constructor() { }
 ngOnInit() {
 }
 onIncrease() {
 this.countNumber++;
 }
 onDecrease() {
 this.countNumber--;
 }
}

3.1.1 功能描述

點(diǎn)擊增加按鈕時(shí)當(dāng)前計(jì)數(shù)會(huì)增加1，點(diǎn)擊減少按鈕時(shí)當(dāng)前計(jì)數(shù)會(huì)剪1

3.1.2 直接在其他組件中使用時(shí)會(huì)報(bào)錯(cuò)

報(bào)錯(cuò)信息如下：

錯(cuò)誤信息是說(shuō)我們我們使用的組件<app-counter>還不是一個(gè)表單控件

3.2 如何讓<app-counter>組件變成一個(gè)表單控件組件

3.2.1 實(shí)現(xiàn) ControlValueAccessor 接口

export class CounterComponent implements OnInit, ControlValueAccessor {
 countNumber: number = 0;
 constructor() { }
 ngOnInit() {
 }
 onIncrease() {
 this.countNumber++;
 }
 onDecrease() {
 this.countNumber--;
 }
 /**將數(shù)據(jù)從模型傳輸?shù)揭晥D */
 writeValue(obj: any): void {
 }
 /**將數(shù)據(jù)從視圖傳播到模型 */
 registerOnChange(fn: any): void {
 }
 registerOnTouched(fn: any): void {
 }
 setDisabledState?(isDisabled: boolean): void {
 }
}

3.2.2 指定依賴信息providers

import { Component, OnInit, forwardRef } from '@angular/core';
import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';
@Component({
 selector: 'app-counter',
 templateUrl: './counter.component.html',
 styleUrls: ['./counter.component.scss'],
 providers: [
 {
 provide: NG_VALUE_ACCESSOR,
 useExisting: forwardRef(() => CounterComponent),
 multi: true
 }
 ]
})
export class CounterComponent implements OnInit, ControlValueAccessor {
 countNumber: number = 0;
 constructor() { }
 ngOnInit() {
 }
 onIncrease() {
 this.countNumber++;
 }
 onDecrease() {
 this.countNumber--;
 }
 /**將數(shù)據(jù)從模型傳輸?shù)揭晥D */
 writeValue(obj: any): void {
 }
 /**將數(shù)據(jù)從視圖傳播到模型 */
 registerOnChange(fn: any): void {
 }
 registerOnTouched(fn: any): void {
 }
 setDisabledState?(isDisabled: boolean): void {
 }
}

3.2.3 待修復(fù)bug

雖然可以正常運(yùn)行，但是表單控件中的元素接受不到使用表單控件那個(gè)組件中表單模型傳過(guò)來(lái)的數(shù)據(jù)，表單控件變化的數(shù)據(jù)也無(wú)法回傳到使用表單控件那個(gè)組件中的表單模型中去；簡(jiǎn)而言之，就是模型和視圖之間無(wú)法進(jìn)行數(shù)據(jù)交互

3.3 實(shí)習(xí)那模型和試圖的數(shù)據(jù)交互

3.3.1 模型到視圖

重構(gòu)自定義表單控件類中的 writeValue 方法

技巧01：writeValue 方法中的參數(shù)是使用自定義表單控件的那個(gè)組件通過(guò)表單的數(shù)據(jù)綁定傳進(jìn)來(lái)的

3.3.2 視圖到模型

》自定義一個(gè)方法來(lái)處理自定義表單控件中的變化數(shù)據(jù)

propagateChange = (_: any) => {};

》重構(gòu)自定義表單控件類中的 registerOnChange 方法

 /**將數(shù)據(jù)從視圖傳播到模型 */
 registerOnChange(fn: any): void {
 this.propagateChange = fn;
 }

》在數(shù)據(jù)變化的地方調(diào)用那個(gè)自定義的方法

3.4 自定義表單控件組件代碼匯總

<div>
 <h4>當(dāng)前計(jì)數(shù)為：{{countNumber}}</h4>
 <br />
 <div>
 <button md-icon-button (click)="onIncrease()">
 <span>增加</span>
 <md-icon>add</md-icon>
 </button>
 <span style="margin-left: 30px;"></span>
 <button md-icon-button (click)="onDecrease()">
 <span>減少</span>
 <md-icon>remove</md-icon>
 </button>
 </div>
</div>

HTML

import { Component, OnInit, forwardRef } from '@angular/core';
import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';
@Component({
 selector: 'app-counter',
 templateUrl: './counter.component.html',
 styleUrls: ['./counter.component.scss'],
 providers: [
 {
 provide: NG_VALUE_ACCESSOR,
 useExisting: forwardRef(() => CounterComponent),
 multi: true
 }
 ]
})
export class CounterComponent implements OnInit, ControlValueAccessor {
 countNumber: number = 0;
 propagateChange = (_: any) => {};
 constructor() { }
 ngOnInit() {
 }
 onIncrease() {
 this.countNumber++;
 this.propagateChange(this.countNumber);
 }
 onDecrease() {
 this.countNumber--;
 this.propagateChange(this.countNumber);
 }
 /**將數(shù)據(jù)從模型傳輸?shù)揭晥D */
 writeValue(obj: any): void {
 this.countNumber = obj;
 }
 /**將數(shù)據(jù)從視圖傳播到模型 */
 registerOnChange(fn: any): void {
 /**fn其實(shí)是一個(gè)函數(shù)，當(dāng)視圖中的數(shù)據(jù)改變時(shí)就會(huì)調(diào)用fn指向的這個(gè)函數(shù)，從而達(dá)到將數(shù)據(jù)傳播到模型的目的 */
 this.propagateChange = fn; // 將fn的指向賦值給this.propagateChange，在需要將改變的數(shù)據(jù)傳到模型時(shí)只需要調(diào)用this.propagateChange方法即可
 }
 registerOnTouched(fn: any): void {
 }
 setDisabledState?(isDisabled: boolean): void {
 }
}

3.5 使用自定義表單控件的那個(gè)組件的代碼匯總

技巧01：如果自定義表單控件和使用自定義表單控件的組件都在不在同一個(gè)模塊時(shí)需要對(duì)自定義表單控件對(duì)應(yīng)組件進(jìn)行導(dǎo)出和導(dǎo)入操作

<div class="panel panel-primary">
 <div class="panel-heading">面板模板</div>
 <div class="panel-body">
 <h3>面板測(cè)試內(nèi)容</h3>
 </div>
 <div class="panel-footer">2018-1-22 10:22:20</div>
</div>

<div class="panel-primary">
 <div class="panel-heading">自定義提取表單控件</div>
 <div class="panel-body">
 <form #myForm=ngForm>
 <app-counter name="counter" [(ngModel)]="countNumber">
 </app-counter>
 </form>
 <h6>綠線上是自定義提取的表單控件顯示的內(nèi)容</h6>
 <hr style="border: solid green 2px" />
 <h6>綠線下是使用自定義表單控件時(shí)表單的實(shí)時(shí)數(shù)據(jù)</h6>
 <h3>表單控件的值為：{{myForm.value | json}}</h3>
 </div>
 <div class="panel-footer">2018-1-31 10:09:17</div>
</div>

<div class="panel-primary">
 <div class="panel-heading">提取表單控件</div>
 <div class="panel-body">
 <form #form="ngForm">
 <p>outerCounterValue value: {{outerCounterValue}}</p>
 <app-exe-counter name="counter" [(ngModel)]="outerCounterValue"></app-exe-counter>
 <br />
 <button md-raised-button type="submit">Submit</button>
 <br />
 <div>
 {{form.value | json}}
 </div>
 </form>
 </div>
 <div class="panel-footer">2018-1-27 21:51:45</div>
</div>

<div class="panel panel-primary">
 <div class="panel-heading">ngIf指令測(cè)試</div>
 <div class="panel-body">
 <button md-rasied-button (click)="onChangeNgifValue()">改變ngif變量</button>
 <br />
 <div *ngIf="ngif; else ngifTrue" >
 <h4 style="background-color: red; color: white" >ngif變量的值為true</h4>
 </div>
 <ng-template #ngifTrue>
 <h4 style="background-color: black; color: white">ngif變量的值為false</h4>
 </ng-template>
 </div>
 <div class="panel-footer">2018-1-27 16:58:17</div>
</div>

<div class="panel panel-primary">
 <div class="panel-heading">RXJS使用</div>
 <div class="panel-body">
 <h4>測(cè)試內(nèi)容</h4>
 </div>
 <div class="panel-footer">2018-1-23 21:14:49</div>
</div>

<div class="panel panel-primary">
 <div class="panel-heading">自定義驗(yàn)證器</div>
 <div class="panel-body">
 <form (ngSubmit)="onTestLogin()" [formGroup]="loginForm">
 <md-input-container>
 <input mdInput placeholder="請(qǐng)輸入登錄名" formControlName="username" />
 </md-input-container>
 <br />
 <md-input-container>
 <input mdInput placeholder="請(qǐng)輸入密碼" formControlName="userpwd" />
 </md-input-container>
 <br />
 <button type="submit" md-raised-button>登陸</button>
 </form>
 </div>
 <div class="panel-footer">2018-1-23 11:06:01</div>
</div>

<div class="panel panel-primary">
 <div class="panel-heading">響應(yīng)式表單</div>
 <div class="panel-body">
 <form [formGroup]="testForm">
 <md-input-container>
 <input mdInput type="text" placeholder="請(qǐng)輸入郵箱" formControlName="email" />
 <span mdSuffix>@163.com</span> 
 </md-input-container>
 <br />
 <md-input-container>
 <input mdInput type="password" placeholder="請(qǐng)輸入密碼" formControlName="password" />
 </md-input-container>
 </form>
 <hr />
 <div>
 <h2>表單整體信息如下：</h2>
 <h4>表單數(shù)據(jù)有效性：{{testForm.valid}}</h4>
 <h4>表單數(shù)據(jù)為：{{testForm.value | json}}</h4>
 <h4>獲取單個(gè)或多個(gè)FormControl：{{testForm.controls['email'] }}</h4>
 <hr />
 <h2>email輸入框的信息如下：</h2>
 <h4>有效性：{{testForm.get('email').valid}}</h4>
 <h4>email輸入框的錯(cuò)誤信息為：{{testForm.get('email').errors | json}}</h4>
 <h4>required驗(yàn)證結(jié)果：{{testForm.hasError('required', 'email') | json}}</h4>
 <h4>minLength驗(yàn)證結(jié)果：{{ testForm.hasError('minLength', 'email') | json }}</h4>
 <h4>hello:{{ testForm.controls['email'].errors | json }}</h4>
 <hr />
 <h2>password輸入框啊的信息如下：</h2>
 <h4>有效性：{{testForm.get('password').valid}}</h4>
 <h4>password輸入框的錯(cuò)誤信息為：{{testForm.get('password').errors | json }}</h4>
 <h4>required驗(yàn)證結(jié)果：{{testForm.hasError('required', 'password') | json}}</h4>
 </div>
 <div>
 <button nd-rasied-button (click)="onTestClick()">獲取數(shù)據(jù)</button>
 <h4>data變量：{{data}}</h4>
 </div>
 </div>
 <div class="panel-footer">2018-1-22 15:58:43</div>
</div>

<div class="panel panel-primary">
 <div class="panel-heading">利用響應(yīng)式編程實(shí)現(xiàn)表單元素雙向綁定</div>
 <div class="panel-body">
 <md-input-container>
 <input mdInput placeholder="請(qǐng)輸入姓名（響應(yīng)式雙向綁定）：" [formControl]="name"/>
 </md-input-container>
 <div>
 姓名為：{{name.value}}
 </div>
 </div>
 <div class="panel-footer">2018-1-22 11:12:35</div>
</div> -->

<div class="panel panel-primary">
 <div class="panel-heading">模板表單</div>
 <div class="panel-body">
 <md-input-container>
 <input mdInput placeholder="隨便輸入點(diǎn)內(nèi)容" #a="ngModel" [(ngModel)]="desc" name="desc" />
 <button type="button" md-icon-button mdSuffix (click)="onTestNgModelClick()">
 <md-icon>done</md-icon>
 </button>
 </md-input-container>
 <div>
 <h3>名為desc的表單控件的值為：{{ a.value }}</h3>
 </div>
 </div>
 <div class="panel-footer">2018-1-22 10:19:31</div>
</div>

<div class="panel panel-primary">
 <div class="panel-heading">md-chekbox的使用</div>
 <div calss="panel-body">
 <div>
 <md-checkbox #testCheckbox color="primary" checked="true">測(cè)試</md-checkbox>
 </div>
 <div *ngIf="testCheckbox.checked">
 <h2>測(cè)試checkbox被選中啦</h2>
 </div>
 </div>
 <div class="panel-footer">2018-1-18 14:02:20</div>
</div> 

<div class="panel panel-primary">
 <div class="panel-heading">md-tooltip的使用</div>
 <div class="panel-body">
 <span md-tooltip="重慶火鍋">鼠標(biāo)放上去</span>
 </div>
 <div class="panel-footer">2018-1-18 14:26:58</div>
</div>


<div class="panel panel-primary">
 <div class="panel-heading">md-select的使用</div>
 <div class="panel-body">
 <md-select placeholder="請(qǐng)選擇目標(biāo)列表" class="fill-width" style="height: 40px;">
 <md-option *ngFor="let taskList of taskLists" [value]="taskList.name">{{taskList.name}}</md-option>
 </md-select>
 </div>
 <div class="panel-footer">2018-1-18 14:26:58</div>
</div> 

<div class="panel panel-primary">
 <div class="panel-heading">ngNonBindable指令的使用</div>
 <div class="panel-body">
 <h3>描述</h3>
 <p>使用了ngNonBindable的標(biāo)簽，會(huì)將該標(biāo)簽里面的元素內(nèi)容全部都看做時(shí)純文本</p>
 <h3>例子</h3>
 <p>
 <span>{{taskLists | json }}</span>
 <span ngNonBindable>← 這是{{taskLists | json }}渲染的內(nèi)容</span>
 </p>
 </div>
 <div class="panel-footer">2018-1-19 09:34:26</div>
</div>

HTML

import { Component, OnInit, HostListener, Inject} from '@angular/core';
import { FormControl, FormGroup, FormBuilder, Validators } from '@angular/forms';
import { Http } from '@angular/http';
import { QuoteService } from '../../service/quote.service';
@Component({
 selector: 'app-test01',
 templateUrl: './test01.component.html',
 styleUrls: ['./test01.component.scss']
})
export class Test01Component implements OnInit {
 countNumber: number = 9;
 outerCounterValue: number = 5; 
 ngif = true;
 loginForm: FormGroup;
 testForm: FormGroup;
 data: any;
 name: FormControl = new FormControl();
 desc: string = 'hello boy';
 taskLists = [
 {label: 1, name: '進(jìn)行中'},
 {label: 2, name: '已完成'}
 ];
 constructor(
 private formBuilder: FormBuilder,
 private http: Http,
 @Inject('BASE_CONFIG') private baseConfig,
 private quoteService: QuoteService
 ) {}
 ngOnInit() {
 this.testForm = new FormGroup({
 email: new FormControl('', [Validators.required, Validators.minLength(4)], []),
 password: new FormControl('', [Validators.required], [])
 });
 this.name.valueChanges
 .debounceTime(500)
 .subscribe(value => alert(value));
 this.loginForm = this.formBuilder.group({
 username: ['', [Validators.required, Validators.minLength(4), this.myValidator], []],
 userpwd: ['', [Validators.required, Validators.minLength(6)], []]
 });
 this.quoteService.test()
 .subscribe(resp => console.log(resp));
 }
 onChangeNgifValue() {
 if (this.ngif == false) {
 this.ngif = true;
 } else {
 this.ngif = false;
 }
 }
 @HostListener('keyup.enter')
 onTestNgModelClick() {
 alert('提交');
 }
 onTestClick() {
 // this.data = this.testForm.get('email').value;
 // console.log(this.testForm.getError);
 console.log(this.testForm.controls['email']);
 }
 onTestLogin() {
 console.log(this.loginForm.value);
 if (this.loginForm.valid) {
 console.log('登陸數(shù)據(jù)合法');
 } else {
 console.log('登陸數(shù)據(jù)不合法');
 console.log(this.loginForm.controls['username'].errors);
 console.log(this.loginForm.get('userpwd').errors);
 }
 }
 myValidator(fc: FormControl): {[key: string]: any} {
 const valid = fc.value === 'admin';
 return valid ? null : {myValidator: {requiredUsername: 'admin', actualUsername: fc.value}};
 }
}

3.6 初始化效果展示

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淺析Angular19 自定義表單控件

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淺析Angular19 自定義表單控件

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