angular-forms

Create a writable signal as the form model, then pass it to the form() function from @angular/forms/signals. Bind inputs in the template with the [formField] directive, and access field state like value(), valid(), and touched() as reactive signals.

Pass a schema callback to the form() function and apply validators like required, email, min, max, minLength, and pattern to schema paths. Custom validators use validate(), async HTTP checks use validateHttp(), and conditional rules accept a when option.

Signal Forms are experimental in Angular v21 and recommended for new projects wanting automatic two-way binding and signal-based state. Reactive Forms remain the production-stable choice, with typed FormGroup, FormBuilder, and FormArray patterns covered in the references.

Use a cross-field validator with validate() on the confirmPassword field, comparing its value against valueOf(schemaPath.password). Return an error object with kind 'mismatch' when the values differ, or null when they match.

Yes, implement the FormValueControl interface with a value model signal and optional inputs like readonly, invalid, and errors. The custom component then binds directly via [formField], as shown in the star rating example.

Avoid Signal Forms when you need production stability guarantees, since the API is experimental in Angular v21. Also skip it for template-driven forms without signals or when using third-party form libraries like Formly or ngx-formly.