ajax POST not working, can't figure why - php

Question

I have a simple AJAX function to send an id of an object to a php page
My function looks like this:
$(function(){
$("a.vote").click(function(){
//get the id
the_id = $(this).attr('id');
alert(the_id);
//ajax post
$.ajax({
type: "POST",
data: "?id="+the_id,
url: "vote.php",
success: function(msg)
{
$("span#message"+the_id).html(msg);
}
});
});
});
My vote.php looks like this:
session_start();
if(isset($_SESSION['user'])) {
// db setup removed
// insert vote into db
$q = "UPDATE votes SET vote = vote + 1 WHERE id = " . $_POST['id'];
mysql_query($q);
echo "You sent " . $_POST['id'];
}
When I execute my AJAX function, it appears that the vote.php is never run
I know that my AJAX function is being called correctly, because alert(the_id); is popping up with the correct ID.
I know my vote.php is functioning correctly because I can run an HTML method="post" with a textbox named "id", and it will update the database correctly.
Can anyone see what's wrong?
Thank you

Answer 1

You're trying to send your variables in the URL, not as POST variables. Should be something like:
$(function(){
$("a.vote").click(function(){
//get the id
var the_id = $(this).attr('id');
alert(the_id);
//ajax post
$.ajax({
type: "POST",
data: {id:the_id},
url: "vote.php",
success: function(msg)
{
$("span#message"+the_id).html(msg);
}
});
});
});
Your data should be as included as an object, not as a string URL. Check out the examples on the jquery API page for more info on this!

Answer 2

The principal thing I see in your code that doesn't look right is data: "?id="+the_id,. The ? is unnecessary, and illogical for a post request. Do the following instead:
data: {
id: the_id
}
This lets jQuery do the URL-encoding for you.
As an additional point, you do $(this).attr(id). This is very inefficient. Do this.id instead, for exactly the same effect hundreds of times quicker at least 20 times quicker.

Answer 3

Your data value shouldn't need a question mark at the beginning.