public function load_children()
{
$db = Database::get_instance();
$sql = "SELECT id FROM subject_types WHERE parent_id=?";
$data = array($this->id);
$query = $db->prepare($sql);
if ($query->execute($data)) {
while ($row = $query->fetch()) {
$new_subject = new SubjectType();
$new_subject->load($row['id']);
$this->children[] = $new_subject;
$new_subject->load_children();
foreach ($new_subject->children as $child) {
$this->children[] = $child;
}
}
}
}
$output .= '</td></tr>';
}
$output .= '</table>';
echo $output;
} else {
echo "false";
}
// end presentation output;
break;
case "list_subjects_of_type":
if (isset($_POST['id'])) {
// This is our SubjectTypeID
$id = trim($_POST['id']);
$current_subject_type = new SubjectType();
$current_subject_type->load($id);
$current_subject_type->load_children();
$sql = "SELECT id FROM subjects WHERE subject_type IN (";
$sql .= $id;
foreach ($current_subject_type->children as $child) {
$sql .= ', ' . $child->id;
}
$sql .= ')';
if ($APP['debug']) {
var_dump($sql);
}
// build the presentation output.
$query = $db->prepare($sql);
if ($query->execute()) {
$subjects_collection = array();
while ($row = $query->fetch()) {
$new_subject = new Subject();
