AI agent skill · by @HoangNguyen0403

Angular Forms

Build typed reactive forms with strict FormGroup typing, custom validators, and nonNullable controls in Angular. Use when implementing typed reactive forms, custom validators, or form control patterns.

Archived 2026-10-23 · Source updated 2026-09-15 · License: MIT. Check the original repository for the latest version.

SKILL.md instructions

# Forms

## **Priority: P2 (MEDIUM)**

## 1. Use Strictly Typed Reactive Forms

- Prefer Reactive Forms to Template-Driven for complex inputs.
- Define typed `FormGroup<T>` with explicit control types — never use untyped FormGroup.

See [typed forms](references/typed-forms.md) for typed FormGroup examples.

## 2. Extract Validation Logic

- Create standalone validator functions in separate file.
- Name the validator module as a separate file (for example, `validators.ts`) in the response and keep validation out of the component class.
- Sync `valueChanges` to stores using `takeUntilDestroyed()`.

See [typed forms](references/typed-forms.md) for standalone validator examples.

## 3. Ensure NonNullable Controls

- Use `fb.nonNullable.group(...)` or `nonNullable: true` on individual controls.
- This ensures form values always strings — avoids null in form values.

## Anti-Patterns

- **No Template-Driven Forms**: Use Reactive Forms for any non-trivial inputs.
- **No untyped FormGroup**: Always use strictly typed `FormGroup<T>`.
- **No validation in component**: Extract into standalone validator functions.

## References

- [Typed Forms](references/typed-forms.md)

## Canonical response anchors

- Additional task-grounded exact anchors: separate file