Optional Fields

Optional Fields

Not every field is required. The optional pseudo-rule lets a field be absent without failing, while still validating it when it is present.

What optional does

optional is not a check — it is a flag. When the field has no value, every other rule queued for it is skipped. When the field is present, the other rules apply as normal.

use InitPHP\Validation\Validation;

// 'nickname' is missing entirely
$v = new Validation([]);
$v->rule('nickname', 'optional|alpha');
$v->validation();   // true — skipped, nothing to check

// 'nickname' is present but invalid
$v = new Validation(['nickname' => '123']);
$v->rule('nickname', 'optional|alpha');
$v->validation();   // false — present, so 'alpha' runs and fails

When is a field "absent"?

A field counts as absent when its key is missing or its value is null. An empty string ('') is considered present, so optional will not skip it:

$v = new Validation(['nickname' => '']);
$v->rule('nickname', 'optional|alpha');
$v->validation();   // false — '' is present, and '' is not alphabetic

If you want to allow blanks too, combine optional with a rule that accepts empty input, or branch on the value before queueing rules:

if (($data['nickname'] ?? '') !== '') {
    $v->rule('nickname', 'alpha|length(2...20)');
}

optional and the lifecycle

optional flags are reset at the end of each validation() run, exactly like the rule queue. So an optional mark only applies to the run it was added in:

$v = new Validation([]);

$v->rule('email', 'optional|required');
$v->validation();   // true — email is optional this run

$v->rule('email', 'required');
$v->validation();   // false — the optional flag did not carry over

This keeps each queue → validate cycle independent. See The Validation Lifecycle.

Marking several fields optional

optional works with piped field names and across separate rule() calls:

$v->rule('phone|fax', 'optional');
$v->rule('phone', 'tel');     // a named pattern, see Patterns & Regex
$v->rule('fax', 'tel');

You can also place optional anywhere in the pipe; order does not matter for it:

$v->rule('middle_name', 'alpha|optional');   // same as 'optional|alpha'

Next

• Rules Reference — the rules you combine with optional.
• The Validation Lifecycle — why flags reset each run.