PHP using exit()

Question

I am using Cakephp but this is a MVC/php doubt

letting the view display the message

vs

echo 'Invalid Data'; exit;

I would like to know is there any pitfalls in the second case like memory leak etc.. Which one is better

EDIT

In case of a ajax call is exit good. and what about memory leak and other issues . Are all variables deallocated

Answer 1

You should use a custom ExceptionHandler (set_error_handler / set_exception_handler) and throw an Exception if you encounter any errors (CakePHP should already provide an ExceptionHandler). Make some space in your view and if the ExceptionHandler/ErrorHandler has a message, show it there to let the user know.

Your second code will just produce a blank page containing the little text. Every user will appreciate if you show the message inside your usual page layout instead of producing a blank page (which looks broken to most people).

Answer 2

In general, you should avoid exit. Exit is an abnormal termination, and programs should not terminate abnormally. Even if an error occurs, there are still many things that needs to be done - cleanup, logging, notifying the user etc. After all, your operating system doesn't reboot every time it cannot open a file.

Answer 3

performance-wise (AJAX cals)

Use exit().

---

user experience-wise (standard site nav)

Show the error in a proper formated page keeping the user within your site.

Answer 4

The Cake tools to signal errors to the user are session messages and error views.

For "passive" actions like view actions, you should throw a 404 or similar, possibly more specialized error, e.g. if the requested model does not exist:

function view($id) {
    $data = $this->Model->read(null, $id);
    if (!$data) {
        $this->cakeError('error404');
    }

    ...
}

See Error Handling with CakePHP.

For any POST action, you should return the user to the view and display an error message using $this->Session->setFlash('Error!') and appropriate error messages for each invalid form field. That's the default behavior of baked views and controllers.

Terminating the whole script with exit makes for a miserable user experience.