SymfonyWorld Online 2021 Summer Edition
June 17 – 18, 2021
SymfonyWorld Online 2021 Winter Edition
December 9 – 10, 2021
  1. Home
  2. Documentation
  3. Reference
  4. Constraints
  5. Null

Warning: You are browsing the documentation for Symfony 2.2, which is no longer maintained.

Read the updated version of this page for Symfony 5.3 (the current stable version).

Null

2.2 version
Unmaintained
2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8

Null

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

Applies to property or method
Options
Class Symfony\Component\Validator\Constraints\Null
Validator Symfony\Component\Validator\Constraints\NullValidator

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:

  • YAML
    1
2
3
4
5
    # src/Acme/BlogBundle/Resources/config/validation.yml
Acme\BlogBundle\Entity\Author:
    properties:
        firstName:
            - 'Null': ~
  • Annotations
     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
    // src/Acme/BlogBundle/Entity/Author.php
namespace Acme\BlogBundle\Entity;

use Symfony\Component\Validator\Constraints as Assert;

class Author
{
    /**
     * @Assert\Null()
     */
    protected $firstName;
}
  • XML
     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
    <!-- src/Acme/BlogBundle/Resources/config/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 http://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">

    <class name="Acme\BlogBundle\Entity\Author">
        <property name="firstName">
            <constraint name="Null" />
        </property>
    </class>
</constraint-mapping>
  • PHP
     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
    // src/Acme/BlogBundle/Entity/Author.php
namespace Acme\BlogBundle\Entity;

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

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

Caution

When using YAML, be sure to surround Null with quotes ('Null') or else YAML will convert this into a null value.

Options

message

type: string default: This value should be null.

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

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