Traverse

Traverse

Object properties are only validated if they are accessible, either by being public or having public accessor methods (e.g. a public getter). If your object needs to be traversed to validate its data, you can use this constraint.

Basic Usage

In the following example, create two classes BookCollection and Book that all have constraints on their properties.

• Annotations

  // src/Entity/BookCollection.php
  namespace App\Entity;
  use Doctrine\Collections\ArrayCollection;
  use Doctrine\Collections\Collection;
  use Doctrine\ORM\Mapping as ORM;
  use Symfony\Component\Validator\Constraints as Assert;
  /**
   * @ORM\Entity
   * @Assert\Traverse
   */
  class BookCollection implements \IteratorAggregate
  {
      /**
       * @var string
       *
       * @ORM\Column
       *
       * @Assert\NotBlank
       */
      protected $name = '';
      /**
       * @var Collection|Book[]
       *
       * @ORM\ManyToMany(targetEntity="App\Entity\Book")
       */
      protected $books;
      // some other properties
      public function __construct()
      {
          $this->books = new ArrayCollection();
      }
      // ... setter for name, adder and remover for books
      // the name can be validated by calling the getter
      public function getName(): string
      {
          return $this->name;
      }
      /**
       * @return \Generator|Book[] The books for a given author
       */
      public function getBooksForAuthor(Author $author): iterable
      {
          foreach ($this->books as $book) {
              if ($book->isAuthoredBy($author)) {
                  yield $book;
              }
          }
      }
      // neither the method above nor any other specific getter
      // could be used to validated all nested books;
      // this object needs to be traversed to call the iterator
      public function getIterator()
      {
          return $this->books->getIterator();
      }
  }

• YAML

  # config/validator/validation.yaml
  App\Entity\BookCollection:
      constraints:
          - Traverse: ~

• 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\BookCollection">
          <constraint name="Traverse"/>
      </class>
  </constraint-mapping>

• PHP

  // src/Entity/BookCollection.php
  namespace App\Entity;
  use Symfony\Component\Validator\Constraints as Assert;
  use Symfony\Component\Validator\Mapping\ClassMetadata;
  class BookCollection
  {
      // ...
      public static function loadValidatorMetadata(ClassMetadata $metadata)
      {
          $metadata->addConstraint(new Assert\Traverse());
      }
  }

When the object implements \Traversable (like here with its child \IteratorAggregate), its traversal strategy will implicitly be set and the object will be iterated over without defining the constraint. It’s mostly useful to add it to be explicit or to disable the traversal using the traverse option. If a public getter exists to return the inner books collection like getBooks(): Collection, the Valid constraint can be used on the $books property instead.

Options

The groups option is not available for this constraint.

traverse

type: boolean default: true

Instances of \Traversable are traversed by default, use this option to disable validating:

• Annotations

  // src/Entity/BookCollection.php
  // ... same as above
  /**
   * ...
   * @Assert\Traverse(false)
   */
   class BookCollection implements \IteratorAggregate
   {
       // ...
   }

• YAML

  # config/validator/validation.yaml
  App\Entity\BookCollection:
      constraints:
          - Traverse: false

• 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\BookCollection">
          <constraint name="Traverse">false</constraint>
      </class>
  </constraint-mapping>

• PHP

  // src/Entity/BookCollection.php
  namespace App\Entity;
  use Symfony\Component\Validator\Constraints as Assert;
  use Symfony\Component\Validator\Mapping\ClassMetadata;
  class BookCollection
  {
      // ...
      public static function loadValidatorMetadata(ClassMetadata $metadata)
      {
          $metadata->addConstraint(new Assert\Traverse(false));
      }
  }

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.