Null

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 Null
Validator 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:

  • Annotations
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    // src/Acme/BlogBundle/Entity/Author.php
    namespace Acme\BlogBundle\Entity;
    
    use Symfony\Component\Validator\Constraints as Assert;
    
    class Author
    {
        /**
         * @Assert\Null()
         */
        protected $firstName;
    }
    
  • YAML
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    # src/Acme/BlogBundle/Resources/config/validation.yml
    Acme\BlogBundle\Entity\Author:
        properties:
            firstName:
                - 'Null': ~
    
  • XML
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    <!-- 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
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    // 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.

payload

type: mixed default: null

2.6The payload option was introduced in Symfony 2.6.

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.

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