Handling PHP exceptions with JQuery

Question

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

Pekka · Accepted Answer · 2010-05-11 11:00:18Z

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.

edited May 11, 2010 at 11:00

answered May 11, 2010 at 10:48

Pekka

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1 Comment

Alejandro Echeverri Over a year ago

Very useful! I had the same problem with jQuery Ajax (The library didn't catch my exceptions thrown from PHP). Sending the Header with the 500 Http Code has solved my problem. Thanks

Jacob Relkin · Accepted Answer · 2010-05-11 10:53:23Z

2

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
            }

edited May 11, 2010 at 10:53

answered May 11, 2010 at 10:48

Jacob Relkin

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Comments

Ionuț G. Stan · Accepted Answer · 2010-05-11 10:48:32Z

0

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

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

answered May 11, 2010 at 10:48

Ionuț G. Stan

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Comments

Tolga Evcimen · Accepted Answer · 2015-12-10 11:59:48Z

-1

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

edited Dec 10, 2015 at 11:59

Tolga Evcimen

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answered Dec 10, 2015 at 10:48

j.m.l

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