Problem with retrieving unlimited categories function

[johnie]

Sorry for reposting but it's urgent and i'm stuck.

function show_subcats($cat_id, $splitter=">", $prev_path="") {
global $catpath;

$cat_sql=mysql_query("SELECT * FROM categories WHERE parent_id=".$cat_id." ORDER BY cat_name");

if (mysql_num_rows($cat_sql)) {
while ($category=mysql_fetch_array($cat_sql)) {
$catpath .= $prev_path.$category["cat_name"].$splitter;

$catpath .= show_subcats($cat_id=$category["cat_id"], $prev_path="$catpath");
}
}

return $catpath;
}

This function is supposed to retrieve all the categories (unlimited depth) from a db by giving a cat_id. The table has parent_id which is 0 for parents, cat_id and cat_name.
I call it with show_subcats($cat_id="0")

However it doesn't work as expected. What's the problem with it?

It must return

Cat1
Cat1>Subcat1
Cat1>Subcat1>Subcat2
Cat1>Subcat2
Cat2
.....
and so on

Thanks,
John

[tbach2]

simplify, simplify.

part of what is confusing is trying to put too much into one statement.

I think you have a couple of things going awry:

1. recursion not being called

2. output will be cumulative
   [/list=1]

   show_subcats($cat_id=$category["cat_id"], $prev_path="$catpath");

   I think this would be the equivalent of saying "show_subcats(1,1)". Assign your value, then pass the value.

   $catpath .= $prev_path.$category["cat_name"].$splitter;

   I think you would want this to be an array, not stringing everything together.

   my advice: get the recursion working (print out results from each iteration), and then work on getting the path info.

[Weedpacket]

Furthering tbach2's post; the line

$catpath .= show_subcats($cat_id=$category["cat_id"], $prev_path="$catpath");

will be the one causing you grief because it

1. sets $cat_id to $category['cat_id'],

2. sets $prev_path to "$catpath", then

3. passes $cat_id and $prev_path as the first two arguments of show_subcats() - the first two arguments being $cat_id and $splitter.

Yes, I know you can do it like this in Perl, but PHP don't play like that.
I suspect

$catpath .= show_subcats($category["cat_id"], $splitter, $catpath);

is what you're intending here. However, I won't say whether such a change will make it actually work.

Incidentally, since you're only using the cat_name and cat_id from the table, things will go much faster if that's all you actually SELECT, instead of selecting everything with *. How much faster depends on how much else is in that table.

[dustbuster]

phence and I had a discussion about this very topic a while ago

http://www.phpbuilder.com/board/showthread.php?s=&threadid=10234093

If you start reading at
"The following code works with the sample data you provided earlier:"

You have a pretty good code sample