/**
	 * Retrieve the vocabulary
	 * @return Array The Term objects in the vocabulary, in tree order
	 **/
	public function get_tree($orderby = 'mptt_left ASC')
	{
		return DB::get_results( "SELECT * FROM {terms} WHERE vocabulary_id=:vid ORDER BY {$orderby}", array('vid' => $this->id), 'Term' );
	}

	/**
	 * Retrieve the vocabulary as an associative array suitable for FormUI select controls
	 * @return Array The Term objects in the vocabulary, in tree order
	 **/
	public function get_options()
	{
		$tree = $this->get_tree('mptt_left ASC');
		$output = array();
		$lastright = $lastleft = reset($tree)->mptt_left;
		$indent = 0;
		$stack = array();
		foreach($tree as $term) {
			while ( count($stack) > 0 && end($stack)->mptt_right < $term->mptt_left ) {
				array_pop($stack);
			}
			$output[$term->id] = str_repeat('- ', count($stack)) . $term->term_display;
			$stack[] = $term;
		}
				
		return $output;
	}