mysql_* functions are deprecated and will eventually not exist in future implementations of PHP. I'd suggest using mysqli. For now, I suppose you're okay.

Atli, on 09 October 2012 - 09:38 AM, said:

What's great about this solution is you can use a custom error handler to catch your trigger_error() calls. Good call on the sanitize function as well.

You're missing one major point. What is the return status of the function?

if( user_exists("foobar")) 
{
   // will this ever execute? 
}
else
{ 
   // or this???
}

	function user_exists($username){
	    $username = sanitize($username);
	    $sql = "SELECT COUNT(`user_id`) FROM `users` WHERE `username` = '$username'";
	    $result = mysql_query($sql);
	    if(!$result) {
	        echo "There was a error in the following sql statement : <br>".$sql;
                //maybe a throw new Exception goes here
	    }
            /* start patch */
	    // Don't you want to return true or false here? 
            if( mysql_num_rows($result) > 0 ) {
              return true; 
            }else {
              return false;
            }
            /* end patch */
	}

*** EDIT ***
wow, I really am batting 1,000 today..

I didn't notice your query was "SELECT COUNT(*)" ... My patch may not work if you use COUNT(*).
Better to change your query to select an ID from the table.

You'll want to check if $stmt is an object after you attempt the db->prepare() function call.

$stmt = $this->db->prepare($sql);
if( is_object($stmt) )
{
    //Alternatively you can opt to return an error rather than throw an exception
    // but you already have a catch statement so might as well make use of it
    throw new Exception("Prepare returned a non-object: " . var_export($stmt,1) );
}

OOPS. The code is supposed to be this:

$stmt = $this->db->prepare($sql);
if( is_object($stmt) == false) //this is the change
{
    //Alternatively you can opt to return an error rather than throw an exception
    // but you already have a catch statement so might as well make use of it
    throw new Exception("Prepare returned a non-object: " . var_export($stmt,1) );
}

I can think of a few ways to solve this

Utilize the bootstrap modal window
http://twitter.githu...javascript.html

I would have the content editor popup in a modal window (preferably bootstrap's). Why?
Well because that would still allow you to pull this off with one page.
When then user submits the content from the content editor, you can submit that via
ajax (encoding it in json), and then refresh the content on page using ajax.

Or, if you don't want to do all that javascript, then as soon as the content editor
saves data, you trigger it to submit in a form. I'm assuming the content editor is a
giant TEXTAREA anyways, so this sort of hackery should be trivial.