Allowing Duplicate Aliases Only Across Different Parents

The built-in “allow duplicate aliases” option is useful for catalogs, but the naive version can still let two identical aliases appear under the same parent. That creates a real collision, not just a convenient reuse of a slug in different branches.

Desired behavior

These URLs should be valid at the same time:

tv/samsung/product.html
photo/samsung/product.html

But two children inside the same parent should not resolve to the exact same alias.

Patch idea

A reliable approach is to checking alias uniqueness against the current parent both for generated aliases and for manually entered aliases. That keeps branch-level reuse while preventing true collisions.

Automatic alias check

else {
    if ($modx->db->getValue("SELECT COUNT(id) FROM " . $tbl_site_content .
        " WHERE id<>'$id' AND parent=$parent AND alias='$alias'") != 0) {
        $cnt = 1;
        $tempAlias = $alias;
        while ($modx->db->getValue("SELECT COUNT(id) FROM " . $tbl_site_content .
            " WHERE id<>'$id' AND parent=$parent AND alias='$tempAlias'") != 0) {
            $tempAlias = $alias . $cnt;
            $cnt++;
        }
        $alias = $tempAlias;
    }
}

Manual alias check

$docid = $modx->db->getValue("SELECT id FROM " . $tbl_site_content .
    " WHERE id<>'$id' AND alias='$alias' AND parent=$parent LIMIT 1");

If the alias already exists under the same parent, stop the save and show the duplicate-alias warning. If it exists only elsewhere in the tree, allow it.

Why this matters

This pattern is especially useful for product catalogs, multilingual branches, and media trees where repeated naming is natural but exact sibling duplicates are not acceptable.