JQuery Sortable PHP to Database - php

Question

So I've got 2 boxes. On the left I have a list of items pulling from the database which I can drag and drop to the right. This works great. I can't for the life of me work out how to get it to post the data for the list on the right and I think I've tried every example Google has to offer this week.
When I do a print_r($_POST); on the page this submits to, I get Array ( ) with nothing in it. It doesn't seem to be grabbing the ID's and serializing them.
Does anyone have experience with this see anything I'm missing?
<script>
$(function() {
$( "ul.droptrue" ).sortable({
connectWith: "ul"
});
$( "ul.dropfalse" ).sortable({
connectWith: "ul",
dropOnEmpty: true
});
$( "#sortable1, #sortable2" ).disableSelection();
});
$( "#sortable2" ).sortable({
axis: 'y',
handle : '.handle',
update: function (event, ui) {
var data = $(this).sortable('serialize');
console.log(data);
// POST to server using $.post or $.ajax
$.ajax({
data: data,
type: 'POST',
url: 'setlists-edit-process.php'
});
}
});
</script>
<ul id="sortable1" class="droptrue">
<?php
$_GET['setlist_id'];
$sql = "SELECT material_id, material_name FROM material WHERE user_id=$session_id";
$result = mysqli_query($conn, $sql);
if (!$result) {
printf("Error: %s\n", mysqli_error($conn));
exit();
}
while($row = mysqli_fetch_array($result))
{
echo "<li id=" . $row['material_id'] . ">" . $row['material_id'] . " | " . $row['material_name'] . "</li>";
}
?>
</ul>
<ul id="sortable2" class="dropfalse">
</ul>

Answer 1

Replace this:
while($row = mysqli_fetch_array($result))
{
echo "<li id=" . $row['material_id'] . ">" . $row['material_id'] . " | " . $row['material_name'] . "</li>";
}
with:
while($row = mysqli_fetch_array($result))
{
echo '<li id="material_' . $row['material_id'] . '">' . $row['material_id'] . " | " . $row['material_name'] . "</li>";
}
Sortable expects the ID to be in the format setname_number.
Moreover, your code outputs in the format id=abc (no quotations), and rather it should be id="abc" with surrounding quotes.