Exception Handlers

Exception Handlers are used to catch and handle Exceptions in Controllers.

Exception Handlers must implement Centum\Interfaces\Router\ExceptionHandlerInterface.

Exception Handlers only require the following public method:

public function handle(Centum\Interfaces\Http\RequestInterface $request, Throwable $throwable): Centum\Interfaces\Http\ResponseInterface

Multiple Exception Handlers can be added to a Router and can be used to handle different types of Exceptions. Within the handle() method, an Centum\Router\Exception\UnsuitableExceptionHandlerException can be thrown so that the Router can try another Exception Handler instead.

Exception Handlers can be used to handle 404 errors by handling RouteNotFoundException:

use App\Web\ExceptionHandlers\RouteNotFoundExceptionHandler;

$router->addExceptionHandler(
    RouteNotFoundExceptionHandler::class
);

namespace App\Web\ExceptionHandlers;

use Centum\Http\Response;
use Centum\Http\Status;
use Centum\Interfaces\Http\RequestInterface;
use Centum\Interfaces\Http\ResponseInterface;
use Centum\Interfaces\Router\ExceptionHandlerInterface;
use Centum\Router\Exception\RouteNotFoundException;
use Centum\Router\Exception\UnsuitableExceptionHandlerException;
use Throwable;

class RouteNotFoundExceptionHandler implements ExceptionHandlerInterface
{
    public function handle(RequestInterface $request, Throwable $throwable): ResponseInterface
    {
        if (!($throwable instanceof RouteNotFoundException)) {
            throw new UnsuitableExceptionHandlerException($this);
        }

        return new Response(
            "Page not found",
            Status::NOT_FOUND
        );
    }
}

In the case that other Exception Handlers are unsuitable for a particular Exception, this example will act as a catch-all for any other Exceptions/Errors. Exception Handlers are processed in the order that they are added to the Application so this should be the very last Exception Handler:

use App\Web\ExceptionHandlers\ThrowableExceptionHandler;

$router->addExceptionHandler(
    ThrowableExceptionHandler::class
);

namespace App\Web\ExceptionHandlers;

use Centum\Http\Response;
use Centum\Http\Status;
use Centum\Interfaces\Http\RequestInterface;
use Centum\Interfaces\Http\ResponseInterface;
use Centum\Interfaces\Router\ExceptionHandlerInterface;
use Throwable;

class ThrowableExceptionHandler implements ExceptionHandlerInterface
{
    public function handle(RequestInterface $request, Throwable $throwable): ResponseInterface
    {
        return new Response(
            "<h1>An error occurred</h1>" .
            "<p>" . get_class($throwable) . "</p>" .
            "<p>" . $throwable->getMessage() . "</p>",
            Status::INTERNAL_SERVER_ERROR
        );
    }
}

Good Practices

It is strongly recommended to have exception handlers for:

Centum\Router\Exception\RouteNotFoundException
Throwable