Codeigniter - detect the sender of a request - ajax

Question

I'm building a commercial website, with a shopping cart.
On most pages (i.e - product page, category page), I want to display the cart contents on a sidebar, which will get updated via AJAX when an item is added to the cart.
On the "display cart" page I want to show a full version of the contents.
Obviously, it seems logical to use the same model and functions to get and/or update the cart, but send the data to a different view (sidebar or full cart), depending on the caller page.
The question is, in the cart model, how can I detect where did the request come from.
I thought I'd check if the request came via AJAX, like so:
if(!empty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest') // i.e - the request came as AJAX
{
$this->load->view('cart_sidebar_view', $data);
}else{ /* not ajax */
$data['main_content'] = 'cart_view';
$this->load->view('includes/template', $data);
}
But that is not good enough, because I want to use AJAX on the "display cart" page as well, to allow updating the cart from there.
So, is there a way to detect, in the cart model, where did the request come from? Or will I have to send that info in a hidden form field with every "add to cart" or "remove" button?

Answer 1

There is a simple way. when you are sending request from the display cart page send an additional variable. Than in the controller check for this variable if variable is coming call a logic if variable is not coming do something else.
if($this->input->is_ajax_request())
{
$this->load->view('cart_sidebar_view', $data);
}else{
if($this->input->post('another_variable')){
// do something else
}else{
$data['main_content'] = 'cart_view';
$this->load->view('includes/template', $data);
}
}