[Ajax] managing Exceptions ..........

[whisher06]

Hi.
I've got some troubles managing exceptions/errors
with ajax.
Now I'm using this method:
Php side:

if(isset($_POST['nickname'])){
header('Content-type: text/html; charset=utf-8');
try {
$db= new DB($options);
$user= new User($db);
$user->insert($_POST['nickname']);

/*return a multidimensional array encoding with json_encode*/
echo $user->getData();
}
catch (InvalidArgException $e) {
/* return a json string */

echo json_encode('Sorry, the server is too busy');
error_log($e->getMessage()."\n", 3, $root."/log/error.log");
exit();
}
catch (DbException $e) {
/* return a json string */

echo json_encode('Sorry, the server is too busy');
error_log($e->getMessage()."\n", 3, $root."/log/error.log");
exit();
}
}


js side:

var user = eval("(" + xhr.responseText + ")");
if(typeof user=='string')
{
//something was wrong :(
}
else
{
//it works ;)
}


Have you got any tips ?

Thanks in advance.

[crux_op]

Ahh... well have you thought about using a Javascript framework?

I use prototype to manage my AJAX calls on the javascript side.

In prototype.... when you make an AJAX call you can set two different functions to process the response: one for when the 200 SUCCESS code is returned and one for when 500 Internal Server error is returned.

Then server side, when I see an error I set the HTTP return code to 500 before I quit the script.

header("HTTP/1.1 500 Internal Server Error");

If you don't use a frame work.. you can still query for the HTTP status with something like this.

if (xmlhttp.readyState==4) {
if (xmlhttp.status==200)
successHandler(xmlhttp.responseText);
else if (xmlhttp.status==500)
errorHandler(xmlhttp.responseText);
}

[whisher06]

Thanks a lot for the tip ;)
errorHandler(xmlhttp.responseText);
Could you give me an example of a errorHandler function, please ;)
Bye.

[crux_op]

Well say in your PHP script, you set the response to be: "Error. This action is evil"....

Then in your HTML, stick a div element to hold error/success messages.

<div id="error"></div>


Then in your javascript. Write an error handler which simply passes the error message generated by PHP into the innerHTML of that div.

Example:

function handleError(errorText)
{
element = document.getElementById(id);
element.innerHTML = errorText;
}