New in Symfony 4.3: JSON validation

February 13, 2019 • Published by Javier Eguiluz

Warning: This post is about an unsupported Symfony version. Some of this information may be out of date. Read the most recent Symfony Docs.

Contributed by
Imad Zairig
in #28477.

JSON is arguably the most used format in applications developed with Symfony. You probably make requests to JSON APIs and send/receive JSON payloads in your projects. That's why Symfony provides a JsonResponse class, a way to build JSON authentication, full JSON support in the Serializer component, a json() helper for controllers, etc.

In Symfony 4.3 we improved the Validator component to add a new Json constraint, which can be applied to properties and getters, and ensures that the given contents are valid JSON contents:

Annotations
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PHP

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        // src/Entity/Book.php
namespace App\Entity;

use Symfony\Component\Validator\Constraints as Assert;

class Book
{
    /**
     * @Assert\Json(message = "This is not valid JSON")
     */
     protected $chapters;
}
    

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        # config/validator/validation.yaml
App\Entity\Book:
    properties:
        chapters:
            - Json:
                message: 'This is not valid JSON'
    

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        <!-- 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 http://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">
    <class name="App\Entity\Book">
         <property name="chapters">
            <constraint name="Json">
                <option name="message">This is not valid JSON</option>
            </constraint>
        </property>
    </class>
</constraint-mapping>
    

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        // src/Entity/Book.php
namespace App\Entity;

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

class Book
{
    protected $chapters;

    public static function loadValidatorMetadata(ClassMetadata $metadata)
    {
        $metadata->addPropertyConstraint('chapters', new Assert\Json(array(
            'message' => 'This is not valid JSON',
        )));
    }
}
    

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Comments

Guillaume Loulier Certified said on Feb 13, 2019 at 10:52

Amazing news!

David Garcia said on Feb 13, 2019 at 11:25

Terrific !!

Oskar Stark said on Feb 13, 2019 at 11:47

Thank you

Kamal ZAIRIG said on Feb 13, 2019 at 11:57

Good news !!

Chaouch abderroauf said on Feb 13, 2019 at 12:24

Good news !! Thanks

Alireza Aghili said on Feb 13, 2019 at 12:53

Well done,

Fabien Papet Certified said on Feb 13, 2019 at 14:13

Finally :-) ! Thank you !

Gemorroj said on Feb 13, 2019 at 14:36

Need more complete work with json in Request object.
example:
```php
public function confirmEmail(Request $request): JsonResponse
{
$token = \json_decode($request->getContent(), true)['token'] ?? null;
return $this->json($token);
}
```
vs
```php
public function confirmEmail(Request $request): JsonResponse
{
// json/getJson... etc.
$token = $request->jsonBody()->get('token');
return $this->json($token);
}
```

shorinmaru said on Feb 13, 2019 at 19:09

Sounds Great. Well done.

DAOUDI Soufian said on Feb 15, 2019 at 06:39

#10

Finally. Thank you!