useFormValid

Returns whether a FormGroup is valid as a signal. The signal updates reactively whenever the form's validity changes.

Usage

import { useFormValid } from 'ng-reactive-utils';

@Component({
  template: `
    <form [formGroup]="form">
      <input formControlName="email" placeholder="Email" />
      <input formControlName="password" type="password" placeholder="Password" />

      <button [disabled]="!isValid()">Submit</button>

      @if (!isValid()) {
        <p class="error">Please fill in all required fields correctly.</p>
      }
    </form>
  `,
})
class LoginFormComponent {
  form = new FormGroup({
    email: new FormControl('', [Validators.required, Validators.email]),
    password: new FormControl('', [Validators.required, Validators.minLength(8)]),
  });

  isValid = useFormValid(this.form);
}

Parameters

Parameter	Type	Default	Description
form	FormGroup	required	The FormGroup to check validity for

Returns

Signal<boolean> - A readonly signal containing the validity state (true if valid)

Notes

• Uses toSignal with form.statusChanges observable
• Returns true when all controls pass validation
• Returns false when any control has validation errors
• Updates reactively when any control's validity changes

Source

import { Signal } from '@angular/core';
import { toSignal } from '@angular/core/rxjs-interop';
import { FormGroup } from '@angular/forms';
import { map } from 'rxjs';

/**
 * Returns whether a FormGroup is valid as a signal.
 * The signal updates reactively whenever the form's validity changes.
 *
 * @param form - The FormGroup to check validity for
 * @returns A signal containing the validity state (true if valid)
 *
 * @example
 * ```typescript
 * @Component({
 *   template: `
 *     <form [formGroup]="form">
 *       <input formControlName="email" />
 *       <button [disabled]="!isValid()">Submit</button>
 *     </form>
 *   `
 * })
 * class MyComponent {
 *   form = new FormGroup({
 *     email: new FormControl('', Validators.required)
 *   });
 *   isValid = useFormValid(this.form);
 * }
 * ```
 */
export const useFormValid = (form: FormGroup): Signal<boolean> => {
  return toSignal(form.statusChanges.pipe(map(() => form.valid)), {
    initialValue: form.valid,
  }) as Signal<boolean>;
};