Create the forum vocabulary if does not exist. Assign the vocabulary a low weight so it will appear first in forum topic create and edit forms. Do not just call forum_enable() because in future versions it might do something different.

File

modules/forum/forum.install, line 107

Code

function forum_update_6000() {
  $ret = array();
  $vid = variable_get('forum_nav_vocabulary', 0);
  $vocabularies = taxonomy_get_vocabularies();
  if (!isset($vocabularies[$vid])) {
    $vocabulary = array(
      'name' => t('Forums'),
      'multiple' => 0,
      'required' => 0,
      'hierarchy' => 1,
      'relations' => 0,
      'module' => 'forum',
      'weight' => -10,
      'nodes' => array(
        'forum' => 1,
      ),
    );
    taxonomy_save_vocabulary($vocabulary);
    variable_set('forum_nav_vocabulary', $vocabulary['vid']);
  }
  return $ret;
}