Codeigniter cache controller issue

I have 2 controllers:

cart/
cart/buy

      

        
        
        
      

    

Both show the contents of the Cart library

    <tbody>
        <?php foreach($this->cart->contents() as $items): ?>
        <tr>
            <td><?php echo $items['name'] ?></td>
            <td>$ <?php echo $this->cart->format_number($items['price']); ?></td>
            <td><?php echo $items['qty'] ?></td>
            <td>$ <?php echo $this->cart->format_number($items['subtotal']); ?></td>
        </tr>
            <?php endforeach; ?>
    </tbody>

      

        
        
        
      

    

My problem is the buy controller stays in the cache when I add the first item to the cart. I mean the cart / controller has 5 items and the cart / buy controller has 1 item. I have to press Ctrl + F5 to see all items

I was able to solve this part:

function buy()
    {

        $this->output->set_header('Last-Modified: ' . gmdate("D, d M Y H:i:s") . ' GMT');
        $this->output->set_header('Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0');
        $this->output->set_header('Pragma: no-cache');
        $this->output->set_header('Expires: Mon, 26 Jul 1997 05:00:00 GMT');  

        if($this->cart->contents())
        {

            $this->load->view('web/products/buy_view');
        }
        else
        {
            redirect('cart');   
        }       

    }

      

        
        
        
      

    

But, you see, I want to know if there is data in the cart and redirect to another page if the cart is empty.

Apparently , if ($ this-> cart-> contents ()) , "remains in the cache", for example, the cart might be filled in cart / but empty in cart / buy , and until I press Ctrl F5, the condition still doesn't work.

Is there a way to fix this, or maybe I am doing something wrong?

pd My add method to cart controller:

function add_item()
    {
        if($this->cart_model->validate_add_item() == TRUE)
        {  
            redirect('cart');
        }
    }

      

        
        
        
      

    

My method of adding to cart model:

function validate_add_item()
    {
        $id = $this->input->post('producto_id'); 
        $cantidad = $this->input->post('cantidad');

        $this->db->select('vNombre, dPrecio');
        $this->db->where('iIdProducto', $id);
        $query = $this->db->get('product', 1);

        if($query->num_rows > 0)
        { 

            foreach ($query->result() as $row)  
            {  

                $data = array(  
                        'id'      => $id,  
                        'qty'=> $cantidad,  
                        'price'  => $row->dPrecio,  
                        'name'  => $row->vNombre  
                );  


                $this->cart->insert($data);   

                return TRUE;    
            }
        }
        else
        {  
            return FALSE;  
        }   
    }