Moodle moodleform::validation() - forms

Question

In my custom plugin I am simply using three drop down and one text box. When I submit the form and validation($data) method is invoked I just get value of state drop down along with the textbox value.
Value of other two drop downs is not returned. I am not sure what I am missing.
Here is my code:
if (!defined('MOODLE_INTERNAL')) {
die('Direct access to this script is forbidden.'); /// It must be included from a Moodle page
}
require_once($CFG->libdir.'/formslib.php');
class ohio_addconfiguration_form extends moodleform {
// Define the form
function definition() {
$id = optional_param('id', 0, PARAM_INT);
$countries = array();
$states = array();
$counties = array();
$cities = array();
$mform =& $this->_form;
// Creating hidden variable id
$mform->addElement('hidden', 'id');
$mform->setType('id', PARAM_INT);
// Creating header "Configuration"
$mform->addElement('header', 'configuration', get_string('ohio', 'local_ohio'));
/* Listing States */
$states_result = $this->get_states("", "1", "id, state_name", "state_name ASC");
if($states_result) {
foreach($states_result as $key=>$state){
$states[$state->id] = $state->state_name;
}
}
$states= count($states)?array(''=>get_string('select_state', 'local_ohio').'...') + $states :array(''=>get_string('select_state', 'local_ohio').'...');
$mform->addElement('select', 'state_id', get_string('select_state', 'local_ohio'), $states);
$mform->addRule('state_id', get_string('required'), 'required', null, 'client');
$mform->setType('state_id', PARAM_INT);
/* Listing Counties */
$counties= array(''=>get_string('select_county', 'local_ohio').'...');
$mform->addElement('select', 'county_id', get_string('select_county', 'local_ohio'), $counties);
$mform->addRule('county_id', get_string('required'), 'required', null, 'client');
$mform->setType('county_id', PARAM_INT);
/* Listing Cities */
$cities= array(''=>get_string('select_city', 'local_ohio').'...');
$mform->addElement('select', 'city_id', get_string('select_city', 'local_ohio'), $cities);
$mform->addRule('city_id', get_string('required'), 'required', null, 'client');
$mform->setType('city_id', PARAM_INT);
// Creating text box for School
$mform->addElement('text', 'school_name', get_string('school_name', 'local_ohio'), 'size="25"');
$mform->setType('school_name', PARAM_TEXT);
$mform->addRule('school_name', get_string('required'), 'required', null, 'client');
$mform->addRule('school_name', get_string('maximumchars', '', 100), 'maxlength', 100, 'client');
$this->add_action_buttons();
}
function validation($data) {
global $DB;
echo "<pre>";
print_r($data);
exit;
}
}

Answer 1

I'm not sure what are you looking for exactly, either form validation or data retrieval, but I'm assuming you're interested in data retrieval and the code you have provided above is written in 'filename_form.php'.
The validation() method is used to validate the data entered in the fields on the server side, and not to get the values of the fields.
To get the values of the fields, you need to create another file named 'filename.php', and include 'filename_form.php' in it for displaying the form.
You can refer here for using Formslib.