I'm trying to create a form whose structure depends on parameters in the URL. If no parameters are specified in the URL, an error message should be displayed. Based on the id, perform a database query and populate the form data.

Example URL: http://127.0.0.1/local/group/signin.php?groupid=14

Unfortunately, when I submit the form by clicking the action button, my form fails to validate. It jumps to http://127.0.0.1/local/group/signin.php and displays the error message "Group not found" because there are no parameters in the URL.

What am I doing wrong here?

signinform.php:

class signinform extends moodleform { public function definition() { global $DB; global $USER; $mform = $this->_form; $urlid = $this->_customdata['id']; // Get the passed group ID $message = 'Group not found'; if(is_null($urlid)){ $mform->addElement('html', '
'.\core\notification::error($message).'
'); } else{ // Build forms, execute SQL queries, etc. $this->add_action_buttons(true, 'Submit'); } } function validation($data, $files) { return array(); } }

Login.php:

$PAGE->set_url(new moodle_url('/local/schedule/signin.php?')); $PAGE->set_context(\context_system::instance()); $PAGE->set_pagelayout('base'); $PAGE->set_title("Register"); $PAGE->set_heading("Register a group"); global $DB; global $USER; $urlid = $_GET["id"]; $to_form = array('id' => $urlid); // Pass the group ID to the form $mform = new signinform(null, $to_form); $homeurl = new moodle_url('/'); if ($mform->is_cancelled()) { redirect($homeurl, 'Cancelled.'); // Only for testing, never enter here } else if ($fromform = $mform->get_data()) { redirect($homeurl, 'Verification in progress'); // Only for testing, never enter here } echo $OUTPUT->header(); $mform->display(); echo $OUTPUT->footer();