checkField<F> method
Creates a new validator by nesting the provided one.
If both the calling validator and the additional check fail, the error produced by the calling is returned. Note: checkField is different from check in that it ignore the verification if the focused field is null. This is common when validating forms in which null represents a field which has not being visited.
Implementation
Validator<S> checkField<F>(
Selector<S, F?> selector,
Validator<F> verification,
) {
final bypassingValidation = _makeOptional(verification);
final Validator<S> fieldValidator = (S s) {
final focus = selector(s);
final result = bypassingValidation(focus);
return result.map((_) => s);
};
return _join(this, fieldValidator);
}