Null.rst

Null

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

Applies to	:ref:`property or method <validation-property-target>`
Options	message
Class	:class:`Symfony\\Component\\Validator\\Constraints\\Null`
Validator	:class:`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:

.. configuration-block::

    .. code-block:: yaml

        # src/Acme/BlogBundle/Resources/config/validation.yml
        Acme\BlogBundle\Entity\Author:
            properties:
                firstName:
                    - 'Null': ~

    .. code-block:: php-annotations

        // src/Acme/BlogBundle/Entity/Author.php
        namespace Acme\BlogBundle\Entity;

        use Symfony\Component\Validator\Constraints as Assert;

        class Author
        {
            /**
             * @Assert\Null()
             */
            protected $firstName;
        }

    .. code-block:: xml

        <!-- 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>

    .. code-block:: php

        // 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.