CodeIgniter validation and checkbox - codeigniter

Question

i have problem with my checkbox i want to add validation but i don't know how should look my name field in validation rule.
My view
<?php
foreach( $tab1 as $row){
?>
<a>
<input type="checkbox" name="<?php echo 'id_user_'.$row->id_user; ?>" value=" <?php echo $row->id_user; ?>" />
</a>
<?php
When i do this i get result (name of the checkbox )for example:
id_user_1
id_user_2
id_user_3
Now i want to add validation but:
$this->form_validation->set_rules(' WHAT SHOULD I WRITE HERE ??? ', 'User','required');
EDIT:
$this->form_validation->set_rules('id_uzytkownika', 'Uzytkownika','required');
if ($this->form_validation->run())
{
$todo = array(
'tytul_projektu'=>$this->input->post('tytul_projektu'),
'opis_projektu'=>$this->input->post('opis_projektu'),
'data_zakonczenia'=>$this->input->post('datepicker')
);
$user_projekty = array(
'id_uzytkownika'=>$this->input->post('id_uzytkownika'),
'id_projektu'=>$this->input->post('id'),
);
$users = array();
foreach($_POST as $key => $value)
{
if(strpos($key, 'id_uzytkownika') === 0)
{
$users[] = $value;
}
}
$this->Todo_model->add($todo,$user_projekty,$users);
VIEW:
<?php
foreach( $tab1 as $row){
?>
<a>
<input type="checkbox" name="<?php echo 'id_uzytkownika['.$row->id_uzytkownika.']'; ?>" value="<?php echo $row->id_uzytkownika; ?>" />
MODEL:
function add($data,$data2,$users)
{
$this->db->insert('projekty', $data);
$id = $this->db->insert_id('projekty');
$data2['id_projektu'] = $id;
$query = $this->db->query("SELECT * FROM uzytkownicy");
foreach($users as $user) {
$data2['id_uzytkownika'] = $user;
$this->db->insert('projekty_uzytkownicy', $data2); }
return $query->result();
}

Answer 1

There are a few approaches you can take with this. Using your existing code, the first would be to create a loop that defines all unique input names.
foreach($users as $user) {
$this->form_validation->set_rules('id_user_'.$user->id_user, 'User','required');
}
However, this logic would require every checkbox to be checked. Which I am not sure in what circumstance this would be used for.
Another approach would be to change your html a little bit.
Instead of
<input type="checkbox" name="<?php echo 'id_user_'.$row->id_user; ?>"
value="<?php echo $row->id_user; ?>" />
you can try using something like
<input type="checkbox" name="<?php echo 'id_user['.$row->id_user.']'; ?>"
value="1" />
This way you could make a form validation rule based on id_user instead of unique names.