Get jQuery Error if PHP Breaks

Question

I have a PHP script that breaks if a variable is not populated and it isn't added to the database, but jQuery handles this as a success and I get this error:

TypeError: Result of expression 'data' [null] is not an object.

Here's the jQuery script:

$.ajax({
    type: "POST",
    url: "/clase/do-add",
    data: $("#adauga").serialize(),
    dataType: "json",
    error: function (xhr, textStatus, errorThrown) { 
        alert('Try again.');
    },
    success: function(data) {
        var dlHTML = '<dl id="' + data.id + '"> [too long] </dl>';
        $('form#adauga').after(dlHTML);
        $('#main dl:first').hide().fadeIn();

        adaugaClasaSubmit.removeAttr('disabled');
        adaugaClasa.removeAttr('readonly');
        adaugaClasa.val("").focus();
    }
});

What is your question? What does your PHP script do when it fails? — Pekka
– Pekka, Commented Dec 24, 2010 at 16:52

lonesomeday · Accepted Answer · 2010-12-24 16:57:26Z

3

The problem is that jQuery's concept of "error" is an HTTP error, not an error that you have noted yourself. If the HTTP response code is <400, jQuery will use your success callback. Your options are (a) to use PHP to give an error in your HTTP response

header("HTTP/1.0 500 Internal Server Error");

or (b) to do your error handling in the success handler:

success: function(data) {
    if (!data) {
        // do your error code here
    } else {
        // do your success code here
    }
}

I prefer the first option, with HTTP response codes, to allow your code to make the best logical sense to a future editor (which may be you!).

answered Dec 24, 2010 at 16:57

lonesomeday

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Comments

Paté · Accepted Answer · 2010-12-24 16:54:10Z

0

success: function(data) {
        if(data!=null){
        ...
        }
}

try this

answered Dec 24, 2010 at 16:54

Paté

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