Question

In my current project I’m querying PHP with normal HTTP-request but also via AJAX where I sometimes return JSON-formatted data and sometimes normal text. When an error occurs, in a normal request, you see the error-message and can do something about it. With AJAX-requests on the other hand you cannot be sure if you get an error or the data you want because it isn’t displayed directly — you just run into troubles because your app won’t work any more.

So I thought about an error-handling-system. My best idea is to send a 500 “Internal Server Error” header if an error occurs, so in my JS, when I send an AJAX-Request, I can simply check for errors that way and handle it.

Unfortunately PHP doesn’t send that kind of header (like when you have a parse-error, or something in your code goes wrong) natively.

Can you:

a) Tell PHP to send headers like 500 if an error occurs? Or
b) Use set_error_handler to send a 500-header and then call PHP regular error handling? Or
c) Can you, in any other way send error headers when a PHP error occurs?

Answer 1

i prefer using Exceptions for handling errors. First, you need to install error-to-exception error handler (http://php.net/manual/en/class.errorexception.php, example 1), then wrap your main application code in a try-catch block and send appropriate headers in the catch part. For example:

try {
    $myApplication->run();
} catch(Exception $e) {
   // log or otherwise register the error
   header('HTTP/1.1 500 Internal Server Error');
}

unfortunately, this doesn’t work with so-called “Fatal errors”, to handle these you have to use stupid tricks like this

ob_start();

register_shutdown_function(function() {
    $p = ob_get_contents();
    if(preg_match('~Fatal error~', $p))
        header('HTTP/1.0 500 Internal Server Error');
});

...your code...