Handling PHP exceptions with JQuery

Question

Hello,

I'm using JQuery to call a PHP function that returns a JSON string upon success or throws some exceptions. Currently I'm calling jQuery.parseJSON() on the response and if it fails I assume the response contains an exception string.

$.ajax({
            type: "POST",
            url: "something.php",
            success: function(response){
                 try {
                     var json = jQuery.parseJSON(response);
                 }
                catch (e) {
                    alert(response);
                    return -1;
                 }
                 // ... do stuff with json
            }

Can anyone suggest a more elegant way to catch the exception?

Many thanks, Itamar

Answer 1

Well, you can have a global exception handler in PHP that would call json_encode on it then echo it out.

<?php
    function handleException( $e ) {
       echo json_encode( $e );
    }
    set_exception_handler( 'handleException' );
?>

You could then check if, say, json.Exception != undefined.

$.ajax({
            type: "POST",
            url: "something.php",
            success: function(response){
                 var json = jQuery.parseJSON( response );
                 if( json.Exception != undefined ) {
                    //handle exception...
                 }
                 // ... do stuff with json
            }

Answer 2

Catch the exception on the PHP end, and output an error message in JSON format:

echo json_encode(array(
    'error' => $e->getMessage(),
));

Answer 3

Catch the exception in your PHP script - using a try .... catch block - and when an exception occurs, have the script output a JSON object with an error message:

 try
  {
     // do what you have to do
  }
 catch (Exception $e)
  {
    echo json_encode("error" => "Exception occurred: ".$e->getMessage());
  }

you would then look for the error message in your jQuery script, and possibly output it.

Another option would be to send a 500 internal server error header when PHP encounters an exception:

try
  {
     // do what you have to do
  }
 catch (Exception $e)
  {
     header("HTTP/1.1 500 Internal Server Error");
     echo "Exception occurred: ".$e->getMessage(); // the response body
                                                   // to parse in Ajax
     die();
  }

your Ajax object will then invoke the error callback function, and you would do your error handling in there.