Ordering an Array with weights? - php

Question

The problem
Right now I have to create this:
In my database; each favorite as its own 'weight' entry.
As of right now it defaults to '10'
Let's say I have an array of favorites,
the weights go like this accordingly:
1
2
3
4
If I were to press the 'down' arrow on '2' I'd have to add +1 to its weight.
Which would result in:
1
3
3
4
But I just want to switch favorite '2' with favorite '3's weight.
I need a way to ensure that when the weights for each item function as they're implied.
Since just adding or subtracting 1 will lead to a lot of problem.
Hopefully I explained it properly.
The code
Writing to the database
/*
* Write Form data to database
*/
function f25_favorites_form_submit($form, &$form_state){
global $user;
$listOfPaths = f25_favorites_listOfPaths();
$selected = $form_state['values']['path'];
$data = array(
'uid' => $user->uid,
'path' => $selected,
'title' => $listOfPaths[$selected]['#title'],
'weight' => 10,
'timestamp' => time(),
);
drupal_write_record(f25_favorites, $data);
}
The Query
/*
* Fetching Specific User's Favorites Data
*/
function f25_favorites_user_favorites() {
global $user;
if($user->uid > 0){
$userid = $user->uid;
$user_paths = db_query("SELECT * FROM f25_favorites foo WHERE foo.uid = '%s' ORDER BY foo.weight DESC", $userid);
$pathlist = array();
while ($data = db_fetch_object($user_paths)) {
$pathlist[] = $data;
}
return $pathlist;
}
}
How should I approach this problem?

Answer 1

if all your favorites are weighted differently, you can simply swap the weight field of the one "getting up" with the one "getting down", or reverse, when decreasing weight. you'd have to figure out the code though

Answer 2

as there are only little items I would save the whole order to the database, not only what has been moved.: i don't know much about drupal but i think it would be easy to accomplish as drupal is php and javascript based.
each element in html has its own id/index (uid?)
<div id="el_1">Menu1</div>
<div id="el_2">Menu2</div>
use javascript to get list of your items in the reordered order (like:
itm[0]=item1;
itm[1]=item3;
itm[2]=item2;
itm[3]=item4;
send itm with ajax to your php updater. and update your db, use the position received and not weights.
now your db has something like this:
uid;position
1;0
3;1
2;2
4;3
I recommend you jquery for the javascript work, jquery has a nice sortable plugin. but it is also awesome for the ajax stuf.