built-in-rules-required.md

Required - verifying that a value is provided

Use the Required rule to ensure that a value is provided (not empty).

By default, a value is considered empty only when it is either:

• Not passed at all.
• null.
• An empty string (after trimming).
• An empty iterable.

Customizing empty condition

Which values are considered empty can be customized via the $emptyCondition option. Unlike in skipOnEmpty, no normalization is performed here, so only a callable or a special class is accepted. For more details see the Empty condition basics section.

An example with custom empty condition that limits empty values to null only:

use Yiisoft\Validator\Rule\Required;
use Yiisoft\Validator\EmptyCondition\WhenNull;

new Required(emptyCondition: new WhenNull());

It's also possible to set it globally for all rules of this type at the handler level via RequiredHandler::$defaultEmptyCondition.

Usage with other rules

Required is rarely used by itself. When combining it with other rules, make sure it's placed first:

use Yiisoft\Validator\Rule\Length;
use Yiisoft\Validator\Rule\Required;

$rules = [
    new Required(),
    new Length(min: 1, max: 50),
];

With these settings, Length will still run in the case of an empty value. To prevent this, set up a conditional validation:

use Yiisoft\Validator\Rule\Length;
use Yiisoft\Validator\Rule\Required;

$rules = [
    new Required(),
    new Length(min: 1, max: 50, skipOnError: true),
];

Other ways of configuring conditional validation are described in the Conditional validation section.