Blank

Blank

Validates that a value is blank - meaning equal to an empty string or null:

if ('' !== $value && null !== $value) {
    // validation will fail
}

To force that a value strictly be equal to null, see the IsNull constraint.

To force that a value is not blank, see NotBlank. But be careful as NotBlank is not strictly the opposite of Blank.

Basic Usage

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

• Annotations

  // src/Entity/Author.php
  namespace App\Entity;
  use Symfony\Component\Validator\Constraints as Assert;
  class Author
  {
      /**
       * @Assert\Blank
       */
      protected $firstName;
  }

• YAML

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

• XML

  <!-- 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="Blank"/>
          </property>
      </class>
  </constraint-mapping>

• PHP

  // 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', new Assert\Blank());
      }
  }

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 blank.

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

You can use the following parameters in this message:

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.