CodeIgniter - form validation with image upload

you need to upload the image when validation is true only. so remove your public function upload_image() and write the functionalists inside validation true statement as given below.

 defined('BASEPATH') OR exit('No direct script access allowed');
class Manage extends MY_Controller
{
    public function __construct()
    {
        parent::__construct();
    }
    public function index()
    {
        $config = array(
            array(
                'field' => 'item_name',
                'label' => 'Item name',
                'rules' => 'required'
            ),
            array(
                'field' => 'item_code',
                'label' => 'Item code',
                'rules' => 'required|is_unique[_items.item_code]'
            ),
            array(
                'field' => 'item_description',
                'label' => 'Item description',
                'rules' => 'required'
            ),
            array(
                'field' => 'item_img',
                'label' => 'Item image',
                'rules' => 'callback_upload_image'
            )
        );

        $this->form_validation->set_rules($config);
        $this->form_validation->set_message('is_unique', 'Item code (' . $this->input->post('item_code') . ') already exists.');

        if($this->form_validation->run() == FALSE)
        {
            // Render the entry form again
        }
        else
        {
           $config['upload_path'] = './items_images';
        $config['max_size'] = 1024 * 10;
        $config['allowed_types'] = 'gif|png|jpg|jpeg';
        $config['encrypt_name'] = TRUE;

        $this->load->library('upload', $config);

        if(isset($_FILES['item_img']) && !empty($_FILES['item_img']['name']))
        {
            if($this->upload->do_upload('item_img'))
            {
                $upload_data = $this->upload->data();
                $_POST['item_img'] = $upload_data['file_name'];
                return TRUE;
            }
            else
            {
                $this->form_validation->set_message('upload_image', $this->upload->display_errors());
                return FALSE;
            }
        }
        else
        {
            $_POST['item_img'] = NULL;
            return FALSE;
        }
    }
  // Go to another page
        }
    }

I found this very helpful post here. The author wrote his own rules to validate the file chosen by user to upload. Code sample:

$this->form_validation->set_rules('file', '', 'callback_file_check');


public function file_check($str){
    $allowed_mime_type_arr = array('application/pdf','image/gif','image/jpeg','image/pjpeg','image/png','image/x-png');
    $mime = get_mime_by_extension($_FILES['file']['name']);
    if(isset($_FILES['file']['name']) && $_FILES['file']['name']!=""){
        if(in_array($mime, $allowed_mime_type_arr)){
            return true;
        }else{
            $this->form_validation->set_message('file_check', 'Please select only pdf/gif/jpg/png file.');
            return false;
        }
    }else{
        $this->form_validation->set_message('file_check', 'Please choose a file to upload.');
        return false;
    }
}