Revision: Sat, 04 Feb 2023 12:24:33 GMT

Filters - Interceptors

Spiral Framework provides a way for developers to customize the behavior of their filters through the use of interceptors. An interceptor is a piece of code that is executed after a filter created, and which allows developers to hook into the filter handling pipeline to perform some action.

Interceptors can be useful for a variety of purposes, such as handling errors or adding additional context to the filter.

To use interceptors you will need to implement the Spiral\Core\CoreInterceptorInterface interface.

Interceptor for filter

Let's imagine that we need to check user authorization to access some filter. We can do it with interceptor:

php
use Spiral\Domain\Annotation\Guarded;

#[Guarded(permission: 'user.store')]
final class StoreUser extends Filter
{
    #[Post]
    public string $username;
    
    #[Post]
    public string $email;
    
    //...
}

Note
Read more about user Role-Based Access Control here.

Here is an example of a simple interceptor that checks authorization:

php
namespace App\Filter;

use Spiral\Attributes\ReaderInterface;
use Spiral\Core\CoreInterceptorInterface;
use Spiral\Core\CoreInterface;
use Spiral\Domain\Annotation\Guarded;
use Spiral\Http\Exception\ClientException\UnauthorizedException;
use Spiral\Security\GuardInterface;

class CheckGuardInterceptor implements CoreInterceptorInterface
{
    public function __construct(
        private readonly GuardInterface $guard,
        private readonly ReaderInterface $reader,
    ) {
    }

    public function process(string $filterClass, string $action, array $parameters, CoreInterface $core): mixed
    {
        $refClass = new \ReflectionClass($filterClass);
        // Read attributes from the filter class and check if it has Guarded annotation
        $guarded = $this->reader->firstClassMetadata($refClass, Guarded::class);

        // If the filter has Guarded attributes, check if the user has the permission
        if ($guarded && !$this->guard->allows($guarded->permission ?: $filterClass)) {
            throw new UnauthorizedException($guarded->errorMessage ?: 'Access denied');
        }

        // If the filter has no Guarded attributes, or the user has the permission, continue
        return $core->callAction($filterClass, $action, $parameters);
    }
}

To use this interceptor, you will need to register it in the configuration file app/config/filters.php.

php

use App\Filter\CheckGuardInterceptor;
use Spiral\Filters\Model\Interceptor\PopulateDataFromEntityInterceptor;
use Spiral\Filters\Model\Interceptor\ValidateFilterInterceptor;

return [    
     'interceptors' => [
        CheckGuardInterceptor::class,
        PopulateDataFromEntityInterceptor::class,
        ValidateFilterInterceptor::class,
     ],
     // ...
];

Note
Pay attention that we have PopulateDataFromEntityInterceptor and ValidateFilterInterceptor in the list, they are required for the filter to work properly.

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