Question

I’m struggling to understand how to get jQuery.ajax to interpret a failed MySQL UPDATE query as an error. Here’s my code:

jQuery:

$.ajax({
    type:'POST',
    url:'/ajax/registration.php',
    data:{formData: formData},
    success:function(data){eformDef.forms.registration.success(data);},
    error:function(data){eformDef.forms.registration.success(data);}
});

PHP

$data = $_POST['formData'];
$firstName = mysql_real_escape_string($data['first name']);
$lastName = mysql_real_escape_string($data['last name']);
$email = mysql_real_escape_string($data['email address']);
$password = mysql_real_escape_string($data['password']);


mysql_query("INSERT INTO users (first_name, last_name, email, password) VALUES ('$firstName', '$lastName', '$email', '$password')") or die(mysql_error());

No matter what–even if I make the mysql_query syntax invalid–the ajax call always interprets the response as a success. I assume that’s because the mysql_error() gets sent back as the response, the ajax call reads that as a string, and apparently considers that to be a success. Of course I can deal with this by checking the response string in the $.ajax success function, but this seems a bit illogical. In cases where I can test for a data type using the $.ajax dataType option, this isn’t an issue. But with an UPDATE query like the one above, I always get a string as a response.

Since there is a workaround (checking the string in the success function), this isn’t a critical issue. But if there is a more correct way of doing this, I’d much prefer that.

Answer 1

PHP will send a 200 OK status no matter what^*, so there is no way to jQuery to detect an error.

You have two possibilities:

• Have the PHP script explicitly output something like “OK” or an JSON encoded array with a status code. Have the jQuery side explicitly look for that “OK” and throw an error if it’s not present.

• Have the PHP script throw an error status code if an error occurs, for example:

    $query = mysql_query(......);
  
    if (!$query)
     {
       header("HTTP/1.1 500 Internal Server Error");
       echo mysql_error(); // Detailed error message in the response body 
       die();
     }
  

^* Except for this exception.