name: form-extraction description: Extract and analyze Angular Reactive Forms from source code for migration comparison and validation. Use when comparing forms between legacy and migrated code.

Form Extraction Skill

Extract and analyze Angular Reactive Forms from source code for migration comparison and validation.

Quick Commands

Extract Form Controls

# From HTML - formControlName
grep -oE 'formControlName="[^"]+"' {path}/**/*.html | sort -u

# From HTML - formGroupName
grep -oE 'formGroupName="[^"]+"' {path}/**/*.html | sort -u

# From TypeScript - form definitions
grep -E '(this\.fb\.group|this\.#fb\.group|this\.fb\.nonNullable\.group|new FormGroup|new UntypedFormGroup)' {path}/**/*.ts

Extract Validators

# Angular Validators (old)
grep -oE 'Validators\.(required|email|minLength|maxLength|min|max|pattern|nullValidator)(\([^)]*\))?' {path}/**/*.ts | sort -u

# OneValidators (new)
grep -oE 'OneValidators\.[a-zA-Z]+(\([^)]*\))?' {path}/**/*.ts | sort -u

# Custom validators
grep -oE '#?[a-zA-Z]+Validator\b' {path}/**/*.ts | sort -u

Form Definition Patterns

Validator Patterns

Validator Mapping (Old → New)

Error Display Patterns

Validators with Built-in Messages (use oneUiFormError directly)

These validators have i18n messages built-in, use simple pattern:

<mat-error oneUiFormError="fieldName"></mat-error>

All Other Validators (MUST use @if/@else)

All validators NOT in the list above need explicit error handling with custom messages:

@if (ctrl.hasError('pattern')) {
  <mat-error>{{ t('validators.your_custom_pattern_message') }}</mat-error>
} @else if (ctrl.hasError('duplicate')) {
  <mat-error>{{ t('validators.duplicate_xxx') }}</mat-error>
} @else {
  <mat-error oneUiFormError="fieldName"></mat-error>
}

References

• Detailed patterns: rules/tools/forms/patterns.md