How can i create reusable input field in Angular?

Question

I am trying to create a reusable field as we do in react. But I failed to do that. I need some suggestions or guidance to fix my issue. Actually, I created a component that holds the input field. Now I want to use that field everywhere in the Angular forms. Please help me to fix this.

Whenever i try to submit it always return undefined.

Any solution appreciated!

Login Form

<Modal [isOpen]="true" title="Login" actionLabel="Sign in" [onSubmit]="handleSubmit">
  <form [formGroup]="loginForm">
    <div class="flex flex-col gap-4">
      <app-input placeholder="Email" type="email" controlName="email"
        (formControlChange)="handleFormControl('email',$event)" />
      <app-input placeholder="Password" type="password" controlName="password"
        (formControlChange)="handleFormControl('password',$event)" />
    </div>
  </form>
</Modal>


export class LoginModalComponent implements OnInit {

  loginForm!: FormGroup;

  constructor(private fb: FormBuilder) { }

  ngOnInit(): void {
    this.loginForm = this.fb.group({
      email: new FormControl(''),
      password: new FormControl('')
    })
  }

  handleFormControl(formControlName: string, formControl: FormControl) {
    this.loginForm.setControl(formControlName, formControl);
  }

  handleSubmit(): void {
    console.log(this.loginForm);
  }
}

Input Component

import { Component, Input, Output, EventEmitter, OnInit } from '@angular/core';
import { FormControl, Validators } from '@angular/forms';

@Component({
  selector: 'app-input',
  template: `
    <input
        [placeholder]="placeholder"
        [formControl]="formControl"
        class="
          w-full
          p-4
          text-lg
          bg-black
          border-2
          border-neutral-800
          rounded-md
          outline-none
          text-white
          focus:border-sky-500
          focus:border-2
          transition
          disabled:bg-neutral-900
          disabled:opacity-70
          disabled:cursor-not-allowed
        "
        [type]="type"
    >
  `,
  styles: [
  ]
})
export class InputComponent implements OnInit {
  @Input('placeholder') placeholder: string = '';
  @Input('controlName') controlName: string = '';
  @Input('type') type: string = 'text';
  @Input() required: boolean = false;
  @Input() email: boolean = false;

  @Output() formControlChange = new EventEmitter<FormControl>();
  formControl!: FormControl;

  ngOnInit(): void {
    this.initializeFormControl()
    this.subscribeToValueChange()
    // this.formControlChange.emit(this.formControl);
  }

  initializeFormControl(): void {
    const validators = [];
    if (this.required) {
      validators.push(Validators.required)
    }

    if (this.email) {
      validators.push(Validators.email);
    }

    this.formControl = new FormControl('', validators);
  }

  subscribeToValueChange(): void {
    this.formControl.valueChanges.subscribe((value) => {
      this.formControlChange.emit(this.formControl);
    })
  }
}

Answer 1

You can use NG_VALUE_ACCESSOR implementation for reusable custom form control components

demo : https://stackblitz.com/edit/angular-module-4xcvpm?file=src%2Fapp%2Fmodel.compoennt.ts

input.component.ts

import { Component, Input, forwardRef, OnInit } from '@angular/core';
import {
  ControlValueAccessor,
  NG_VALUE_ACCESSOR,
  Validators,
  FormControl,
  ValidatorFn,
} from '@angular/forms';

@Component({
  selector: 'app-input',
  template: `
    <input
        [placeholder]="placeholder"
        [formControl]="formControl"
        class="
          w-full
          p-4
          text-lg
          bg-black
          border-2
          border-neutral-800
          rounded-md
          outline-none
          text-white
          focus:border-sky-500
          focus:border-2
          transition
          disabled:bg-neutral-900
          disabled:opacity-70
          disabled:cursor-not-allowed
        "
        [type]="type"
    >`,
  providers: [
    {
      provide: NG_VALUE_ACCESSOR,
      useExisting: forwardRef(() => InputComponent),
      multi: true,
    },
  ],
  styles: [],
})
export class InputComponent implements OnInit, ControlValueAccessor {
  @Input('placeholder') placeholder: string = '';
  @Input('type') type: string = 'text';
  @Input() required: boolean = false;
  @Input() email: boolean = false;

  formControl!: FormControl;
  onTouched: any;
  onChange: any;

  ngOnInit(): void {
    const validators: ValidatorFn[] = [];

    if (this.required) {
      validators.push(Validators.required);
    }

    if (this.email) {
      validators.push(Validators.email);
    }

    this.formControl = new FormControl('', validators);
  }

  writeValue(value: any): void {
    this.formControl.setValue(value);
  }

  registerOnChange(fn: any): void {
    this.onChange = fn;
    this.formControl.valueChanges.subscribe(fn);
  }

  registerOnTouched(fn: any): void {
    this.onTouched = fn;
  }

  setDisabledState(isDisabled: boolean): void {
    isDisabled ? this.formControl.disable() : this.formControl.enable();
  }
}

login-modal.component.ts

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';

@Component({
  selector: 'app-login-modal',
  template: `
    <Modal [isOpen]="true" title="Login" actionLabel="Sign in" (submit)="handleSubmit()">
      <form [formGroup]="loginForm">
        <div class="flex flex-col gap-4">
          <app-input placeholder="Email" type="email" required="true" email="true" formControlName="email"></app-input>
          <app-input placeholder="Password" type="password" required="true" formControlName="password"></app-input>
        </div>
      </form>
    </Modal>
  `,
  styles: [],
})
export class LoginModalComponent implements OnInit {
  loginForm!: FormGroup;

  constructor(private fb: FormBuilder) {}

  ngOnInit(): void {
    this.loginForm = this.fb.group({
      email: ['', [Validators.required, Validators.email]],
      password: ['', Validators.required],
    });

    this.loginForm.get('email')!.valueChanges.subscribe((value) => {
      console.log('email value changed:', value);
    });

    this.loginForm.get('password')!.valueChanges.subscribe((value) => {
      console.log('password value changed:', value);
    });
  }

  handleSubmit(): void {
    console.log('heloo');
    console.log(this.loginForm.value);
  }
}

modal.component.ts

import { Component, Input, Output, EventEmitter } from '@angular/core';

@Component({
  selector: 'Modal',
  template: `
    <div *ngIf="isOpen" class="modal">
      <h2>{{ title }}</h2>
      <ng-content></ng-content>
      <button (click)="submit.emit()">{{ actionLabel }}</button>
    </div>
  `,
})
export class ModalComponent {
  @Input() isOpen: boolean = false;
  @Input() title: string = '';
  @Input() actionLabel: string = '';
  @Output() submit = new EventEmitter<void>();
}