Hi,

there's no direct way to get the number of products in a given category (i.e. with JomGenius) but you should be able to get the info with a database call. Once you have that, MetaMod can do the module switching.

Try this:

$vm = JomGenius("virtuemart");
if (!$vm->check("pagetype = category")) return; // show nothing if not on a category page
$cat = $vm->info("category_id");
if (!$cat) return; // show nothing if we can't get a category id
$query = 'select count(*) from #_' . '_virtuemart_product_categories where virtuemart_category_id = \'' . (int)$cat . '\'';
$db->setQuery($query);
$c = $db->loadResult();
if ($c == 0) return XXX;
// replace XXX with module id of module to display on category pages with no products

I think i fixed it! I used if($c > 1) and it works like a charm!

Actually one reason it didn't work may be that the SQL code above does not check to see if the products are actually published/showing or not. It just checks to see if the products are associated with a category. Could it be that for the categories that weren't working (i.e. not showing as empty when they should have been) actually contained a product that was disabled/unpublished in some way?