Forms — Template-Driven & Reactive — Angular Fundamentals | Sabaoon Academy

Angular has two form strategies. Template-driven forms keep logic in the template — great for simple forms. Reactive forms keep logic in the component class — better for complex validation, dynamic fields, and testing.

Template-Driven Forms

Requires FormsModule in your module. Use ngModel to bind inputs:

// app.module.ts
import { FormsModule } from '@angular/forms';
@NgModule({ imports: [FormsModule, ...] })

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export class LoginComponent {
  model = { email: '', password: '' }

  onSubmit(form: NgForm) {
    if (form.valid) console.log(this.model)
  }
}

Reactive Forms

Requires ReactiveFormsModule. Define the form structure in the component class:

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

export class RegisterComponent implements OnInit {
  form!: FormGroup

  constructor(private fb: FormBuilder) {}

  ngOnInit() {
    this.form = this.fb.group({
      name:     ['', [Validators.required, Validators.minLength(2)]],
      email:    ['', [Validators.required, Validators.email]],
      password: ['', [Validators.required, Validators.minLength(8)]],
    })
  }

  get name()     { return this.form.get('name')! }
  get email()    { return this.form.get('email')! }
  get password() { return this.form.get('password')! }

  onSubmit() {
    if (this.form.valid) console.log(this.form.value)
  }
}

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Live Form Example

Here's a registration form with real-time validation — the kind Angular would generate:

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var nameEl     = document.getElementById('name');
var emailEl    = document.getElementById('email');
var passwordEl = document.getElementById('password');
var submitEl   = document.getElementById('submit');
var successEl  = document.getElementById('success');

nameEl.addEventListener('blur', function() {
validate(this, 'nameError', function(v) {
  return v.trim().length < 2 ? 'Name must be at least 2 characters.' : '';
});
});

emailEl.addEventListener('blur', function() {
validate(this, 'emailError', function(v) {
  return /^[^s@]+@[^s@]+.[^s@]+$/.test(v) ? '' : 'Enter a valid email.';
});
});

passwordEl.addEventListener('blur', function() {
validate(this, 'passwordError', function(v) {
  return v.length >= 8 ? '' : 'Password must be 8+ characters.';
});
});

if (ok) {
  successEl.textContent = 'Account created for ' + emailEl.value + '!';
  console.log('Form submitted:', { name: nameEl.value, email: emailEl.value });
}
});

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Built-in Validators

Validator	What it checks
`Validators.required`	Field is not empty
`Validators.email`	Valid email format
`Validators.minLength(n)`	At least `n` characters
`Validators.maxLength(n)`	At most `n` characters
`Validators.pattern(regex)`	Matches a regex
`Validators.min(n)`	Number ≥ n
`Validators.max(n)`	Number ≤ n

You can also write custom validators — a function that returns null (valid) or an error object.