Filtering a Resource List with a Select Form in Evolution CMS

A common Evolution CMS pattern is to use a form select as a lightweight filter: each option stores the ID of a container resource, and after submission the site displays the children of that selected container.

Basic idea

Submit the selected parent ID, validate it, and pass it into your listing snippet as the new source scope.

$parent = isset($_GET['parent']) ? (int)$_GET['parent'] : 0;
if ($parent > 0) {
    echo $modx->runSnippet('Ditto', array(
        'parents' => $parent,
        'tpl' => 'listingRow'
    ));
}

Why this works well

• the form stays simple
• the resource tree remains your data model
• you avoid duplicating category logic in custom SQL

Recommendation

If the filter logic later grows beyond one parent selector, that is a good moment to move toward a richer filtering layer. But for container-based category switching, this is still a solid starting point.