angular-forms

Angular forms: Signal Forms (experimental) and Reactive Forms. Trigger: When working with forms, validation, or form state in Angular.

SKILL.md

GitHub

When to Use What

Use Case Recommendation
New apps with signals Signal Forms (experimental)
Production apps Reactive Forms
Simple forms Template-driven

Signal Forms (v21+, experimental)

import { form, FormField, required, email } from '@angular/forms/signals';

@Component({
  imports: [FormField],
  template: `
    <form>
      <input [formField]="emailField" type="email" />
      <input [formField]="passwordField" type="password" />
      <button (click)="submit()">Login</button>
    </form>
  `
})
export class LoginComponent {
  readonly loginForm = form({
    email: ['', [required, email]],
    password: ['', required]
  });
  
  readonly emailField = this.loginForm.controls.email;
  readonly passwordField = this.loginForm.controls.password;
  
  submit() {
    if (this.loginForm.valid()) {
      const values = this.loginForm.value();
    }
  }
}

Signal Forms Benefits

  • Automatic two-way binding
  • Type-safe field access
  • Schema-based validation
  • Built on signals

Reactive Forms (production)

import { FormBuilder, Validators, ReactiveFormsModule } from '@angular/forms';

@Component({
  imports: [ReactiveFormsModule],
  template: `
    <form [formGroup]="form" (ngSubmit)="submit()">
      <input formControlName="email" type="email" />
      <input formControlName="password" type="password" />
      <button type="submit" [disabled]="form.invalid">Login</button>
    </form>
  `
})
export class LoginComponent {
  private readonly fb = inject(FormBuilder);

  form = this.fb.nonNullable.group({
    email: ['', [Validators.required, Validators.email]],
    password: ['', [Validators.required, Validators.minLength(8)]],
  });
  
  submit() {
    if (this.form.valid) {
      const { email, password } = this.form.getRawValue();
    }
  }
}

Key Points

  • ALWAYS use fb.nonNullable.group() for type safety
  • Use getRawValue() to get typed values
  • Reactive Forms are synchronous (easier to test)

Nested Forms & FormArray

form = this.fb.nonNullable.group({
  name: [''],
  address: this.fb.group({
    street: [''],
    city: [''],
  }),
  phones: this.fb.array([this.fb.control('')]),
});

get phones() {
  return this.form.get('phones') as FormArray;
}

addPhone() {
  this.phones.push(this.fb.control(''));
}

Resources