Custom Exception Handling in Kohana3

Question

I have a requirement to create custom exception for the exceptions generated by my app/module.

• I want to consolidate all the exception classes in one place and h

Answer 1

I would suggest you to move to Kohana 3.2 as there is a change in the way Kohana handles exception in that new stable version. Assuming you are going to use v3.2, this is how you could manage custom exceptions:

First of all, you need to modify bootstrap.php and make sure 'errors' is to true in the Kohana::init() call. This will make sure that Koahana will handle all unhandled exceptions thrown by you or the system. if you check \classes\kohana\core.php, Kohana registers its exception handler class Kohana_Exception using php call below

set_exception_handler(array('Kohana_Exception', 'handler'));

The default exception handler does a nice job of handling all types of Exceptions and writing the message to the log folder and displaying a basic error page. If you look inside Kohana_Exception, it is a subclass of Kohana_Kohana_Exception class, which is where the logic is written.

Now, to customize things:

• If you are looking for just showing a custom page for showing your errors, just create a view named application/views/kohana/error.php and put your custom error page there. it will override the system's default error view file found at system/views/kohana/error.php.

• If you are looking for changing the way you log the error or do some custom processing based on specific type of errors, you need to override Kohana_Exception class or register your own derived exception handler by calling set_exception_handler() at the end of bootstrap.php.

  • To override Kohana_Exception, just copy paste /system/classes/kohana/exception.php to application/classes/kohana/exception.php and override the handler() and/or text() method. for e.g. below I am custom handling 404 error and also including user_id to error log for debugging.

:

class Kohana_Exception extends Kohana_Kohana_Exception 
{
    /**
     * Overriden to show custom page for 404 errors
     */
    public static function handler(Exception $e)
    {
        switch (get_class($e))
        {
            case 'HTTP_Exception_404':
                $response = new Response;
                $response->status(404);
                $view = new View('error/report_404');
                $view->message = $e->getMessage();
                echo $response->body($view)->send_headers()->body();
                if (is_object(Kohana::$log))
                {
                    // Add this exception to the log
                    Kohana::$log->add(Log::ERROR, $e);
                    // Make sure the logs are written
                    Kohana::$log->write();
                }                
                return TRUE;
                break;

            default:
                return Kohana_Kohana_Exception::handler($e);
                break;
        }
    }

  /**
    * Override if necessary.  E.g. below include logged in user's info in the log
   */
   public static function text(Exception $e)
   {

    $id = <get user id from session>;
    return sprintf('[user: %s] %s [ %s ]: %s ~ %s [ %d ]',
            $id, get_class($e), $e->getCode(), strip_tags($e->getMessage()), Debug::path($e->getFile()), $e->getLine());        

   }
}

Helpful external links and references:

http://kohana.sebicas.com/index.php/guide/kohana/errors

http://kohanaframework.org/3.1/guide/kohana/tutorials/error-pages