passing multiple values from input checkbox in codeigniter not working

i have a codeignter form, from where i try to pass values of multiple checkboxes and display it in another view page, the view is like:

<tbody>
  <?php
     $i=1;
    foreach($selectexcel as $val){?>
    <tr>
      <th scope="col"><input type="checkbox" id="checkItem" name="printtype[]" value="<?=$val->id?>" /></th>
      <th scope="row">
        <?= $i?>
      </th>
      <th scope="row"><?= $i?></th>
      <td><?= $val->batchnumber?></td>
    
      <td>
        <button type="submit" name="savemeda" style="margin-left:5px; font-size: 0.6em;" class="btn btn-warning">PRINT</button></td>
    </tr>
    <?php $i++; } ?>
</tbody>

below is my controller:

  public function printconsignment() {
    $data = array();
    if($this->isUserLoggedIn){
        $con = array(
            'id' => $this->session->userdata('userId')
        );

            if(isset($_POST['savemeda']))
            {
                $user_id=1;//Pass the userid here
                $checkbox = $_POST['printtype'];
                for($i=0;$i<count($checkbox);$i++){
                    $ding = $checkbox[$i];
          $data['catil'] = $this->excel_import_model->selectprint($ding);


                }}

        $this->load->model('excel_import_model');

        $this->load->view('printconsignment',$data);

        }



}

and finally my model is like below:

    public function selectprint($catil) {
                $this->db->select('*');
                $this->db->where("id", $catil);
                $this->db->from('fileupload');
             $query = $this->db->get();
             $result = $query->result();
             return $result;

    }

when i try to pass one checkbox value, its successfully passing to the next page, but when i try to select multiple checkbox, its not happening, any one value is being displayed in the next page, can anyone please tell me what is wrong here, thanks in advance