where filter for Category sections

Hi aev, 

There's no support for 'where' with getCategories() because any filtering would cause the hierarchy to not display correctly or have gaps in it.

Some alternatives would be to use the standard getRecords() instead and manually indent records based on $categoryRecord['depth'].

Or if you're displaying all the categories then move your where/filter code inside the foreach block and just skip records you don't want with something like:

<?php
  <?php echo $categoryRecord['_listItemStart'] ?>

  if (!contains('test', $categoryRecord['title'])) {  // skip records without "test" in title
    echo $categoryRecord['_listItemEnd'];             // print closing </li> etc for this branch
    continue;  
  }
?>

Alternatively, if you're just trying to display a specific branch, you could just load those with a direct query (just get all the records with a parentNum of 123, etc.

Let me know if one of those options will work for you.