Sonata Media - file extension validation in admin

Sonata Media is a media management bundle for Symfony that allows you to handle media files (images, videos, documents) in your application. To add file extension validation in the Sonata Media Admin, you can use Symfony's built-in form validation and constraints.

Here's a step-by-step guide to adding file extension validation in the Sonata Media Admin:

1. Install Required Libraries: Make sure you have Sonata Media and Symfony's Validator component installed in your project. If you haven't already, install them using Composer:

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composer require sonata-project/media-bundle
composer require symfony/validator

2. Define the File Extension Constraint: Create a new constraint class to define the file extension validation. In this example, we'll create a constraint that only allows .jpg, .png, and .gif file extensions.

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// src/Validator/Constraints/AllowedFileExtension.php

namespace App\Validator\Constraints;

use Symfony\Component\Validator\Constraint;

/**
 * @Annotation
 */
class AllowedFileExtension extends Constraint
{
    public $message = 'Only files with the extensions ".jpg", ".png", and ".gif" are allowed.';
}

3. Implement the Validator for the Constraint: Create a custom validator that checks the file extension against the allowed extensions defined in the constraint.

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// src/Validator/Constraints/AllowedFileExtensionValidator.php

namespace App\Validator\Constraints;

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;

class AllowedFileExtensionValidator extends ConstraintValidator
{
    public function validate($value, Constraint $constraint)
    {
        if ($value instanceof \SplFileInfo) {
            $allowedExtensions = ['jpg', 'png', 'gif'];
            $fileExtension = strtolower($value->getExtension());

            if (!in_array($fileExtension, $allowedExtensions)) {
                $this->context->buildViolation($constraint->message)
                    ->addViolation();
            }
        }
    }
}

4. Register the Constraint and Validator as Services: Register the constraint and the validator as services in Symfony's service container.

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# config/services.yaml

services:
    App\Validator\Constraints\AllowedFileExtension:
        tags:
            - { name: validator.constraint_validator }

    App\Validator\Constraints\AllowedFileExtensionValidator:
        tags:
            - { name: validator.constraint_validator, alias: allowed_file_extension_validator }

5. Use the Constraint in the Media Admin: Now you can use the created constraint in the Sonata Media Admin configuration. Open your Sonata Admin class (e.g., MediaAdmin) and add the constraint to the form field that handles file uploads.

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// src/Admin/MediaAdmin.php

namespace App\Admin;

use App\Validator\Constraints\AllowedFileExtension;
use Sonata\AdminBundle\Admin\AbstractAdmin;
use Sonata\AdminBundle\Form\FormMapper;

class MediaAdmin extends AbstractAdmin
{
    protected function configureFormFields(FormMapper $formMapper)
    {
        $formMapper
            // Other fields...
            ->add('binaryContent', 'file', [
                'label' => 'File',
                'required' => false,
                'constraints' => [
                    new AllowedFileExtension(),
                ],
            ]);
    }
}

With these steps, you've added file extension validation to the Sonata Media Admin. Now, when uploading media files, only files with the extensions .jpg, .png, and .gif will be allowed. If a user tries to upload a file with a different extension, the form will display an error message.

Please note that the exact implementation might vary depending on your specific Symfony and Sonata Media version. Always consult the official documentation and version-specific guides for the most accurate information.