IsNull

Validates that a value is exactly equal to null. To force that a property is blank (blank string or null), see the Blank constraint. To ensure that a property is not null, see NotNull.

Also see NotNull.

Applies to	property or method
Class	IsNull
Validator	IsNullValidator

Basic Usage

If, for some reason, you wanted to ensure that the firstName property of an Author class exactly equal to null, you could do the following:

Annotations
Attributes
YAML
XML
PHP

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        // src/Entity/Author.php
namespace App\Entity;

use Symfony\Component\Validator\Constraints as Assert;

class Author
{
    /**
     * @Assert\IsNull
     */
    protected $firstName;
}
    

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        // src/Entity/Author.php
namespace App\Entity;

use Symfony\Component\Validator\Constraints as Assert;

class Author
{
    #[Assert\IsNull]
    protected $firstName;
}
    

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        # config/validator/validation.yaml
App\Entity\Author:
    properties:
        firstName:
            - 'IsNull': ~
    

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        <!-- config/validator/validation.xml -->
<?xml version="1.0" encoding="UTF-8" ?>
<constraint-mapping xmlns="http://symfony.com/schema/dic/constraint-mapping"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping https://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">

    <class name="App\Entity\Author">
        <property name="firstName">
            <constraint name="IsNull"/>
        </property>
    </class>
</constraint-mapping>
    

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        // src/Entity/Author.php
namespace App\Entity;

use Symfony\Component\Validator\Constraints as Assert;
use Symfony\Component\Validator\Mapping\ClassMetadata;

class Author
{
    public static function loadValidatorMetadata(ClassMetadata $metadata)
    {
        $metadata->addPropertyConstraint('firstName', Assert\IsNull());
    }
}
    

Options

`groups`

type: array | string

It defines the validation group or groups this constraint belongs to. Read more about validation groups.

`message`

type: string default: This value should be null.

This is the message that will be shown if the value is not null.

You can use the following parameters in this message:

Parameter	Description
`{{ value }}`	The current (invalid) value
`{{ label }}`	Corresponding form field label

`payload`

type: mixed default: null

This option can be used to attach arbitrary domain-specific data to a constraint. The configured payload is not used by the Validator component, but its processing is completely up to you.

For example, you may want to use several error levels to present failed constraints differently in the front-end depending on the severity of the error.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.