Angular
Building a Custom Form Control in Angular with ControlValueAccessor
Introduction
Creating a custom form control in Angular allows better control over form inputs, ensuring flexibility and reusability.
Why Use ControlValueAccessor?
Works smoothly with Angular’s reactive and template-driven forms.
Provides a reusable approach to handling custom input components.
Enables two-way data binding without additional boilerplate code.
Create a Custom Form Control Component
import { Component, forwardRef } from '@angular/core';import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';@Component({selector: 'app-custom-input',template: '<input [value]="value" (input)="onInput($event.target.value)" />',providers: [{provide: NG_VALUE_ACCESSOR,useExisting: forwardRef(() => CustomInputComponent),multi: true}]})export class CustomInputComponent implements ControlValueAccessor {value: string = '';onChange: (value: string) => void = () => {};onTouched: () => void = () => {};writeValue(value: string): void {this.value = value;}registerOnChange(fn: any): void {this.onChange = fn;}registerOnTouched(fn: any): void {this.onTouched = fn;}onInput(value: string) {this.value = value;this.onChange(value);}}Use the Custom Control in a Form
<form [formGroup]="form"><app-custom-input formControlName="customField"></app-custom-input></form>Register in a Reactive Form
import { Component } from '@angular/core';import { FormControl, FormGroup } from '@angular/forms';@Component({selector: 'app-root',templateUrl: './app.component.html'})export class AppComponent {form = new FormGroup({customField: new FormControl('')});}Conclusion
ControlValueAccessor enables seamless integration of custom form controls in Angular applications. By implementing this interface, you ensure consistent behavior with Angular’s form APIs, enhancing usability and maintainability.
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