/**
  * Paginate documents by category
  *
  * @param DocumentCategory $category
  * @param integer	$min_visibility
  * @param integer $page
  * @param integer $per_page
  * @return array
  */
 function paginateByCategory($category, $min_visibility = VISIBILITY_PRIVATE, $page = 1, $per_page = 30)
 {
     return Documents::paginate(array('conditions' => array('category_id = ? AND visibility >= ?', $category->getId(), $min_visibility), 'order' => 'is_pinned DESC, name'), $page, $per_page);
 }