public function validate($data) {
        global $DB, $SITE;
        $cleaned = clean_param($data, PARAM_TEXT);
        if ($cleaned === '') {
            return get_string('required');
        }
        if ($this->name ==='shortname' &&
                $DB->record_exists_sql('SELECT id from {course} WHERE shortname = ? AND id <> ?', array($data, $SITE->id))) {
            return get_string('shortnametaken', 'error', $data);
        }
        if ("$data" == "$cleaned") { // implicit conversion to string is needed to do exact comparison
            return true;
        } else {
            return get_string('validateerror', 'admin');
        }
    }
public function validate($data) {
        global $DB, $SITE;
        $cleaned = clean_param($data, PARAM_TEXT);
        if ($cleaned === '') {
            return get_string('required');
        }
        if ($this->name ==='shortname' &&
                $DB->record_exists_sql('SELECT id from {course} WHERE shortname = ? AND id <> ?', array($data, $SITE->id))) {
            return get_string('shortnametaken', 'error', $data);
        }
        if ("$data" == "$cleaned") { // implicit conversion to string is needed to do exact comparison
            return true;
        } else {
            return get_string('validateerror', 'admin');
        }
    }
public function validate ( $ data ) { global $ DB , $ SITE ; $ cleaned = clean_param ( $ data , PARAM_TEXT ) ; if ( $ cleaned === '' ) { return get_string ( 'required' ) ; } if ( $ this -> name === 'shortname' && $ DB -> record_exists_sql ( 'SELECT id from {course} WHERE shortname = ? AND id <> ?' , array ( $ data , $ SITE -> id ) ) ) { return get_string ( 'shortnametaken' , 'error' , $ data ) ; } if ( "$data" == "$cleaned" ) { // implicit conversion to string is needed to do exact comparison return true ; } else { return get_string ( 'validateerror' , 'admin' ) ; } }
Validate the selected data

@param string $data The selected value to validate
@return mixed true or message string
Validate the selected data