I have done this using cakephp. Hope this will be helpful to you. To add product to your cart add the following function to your Controller file:

public function product(){
    //find all products
    $products = $this->Product->find('all');

    //set counter to display number of products in a cart
    $counter = 0;


    if ($this->Session->read('Counter')) {
        $counter = $this->Session->read('Counter');
    }
    //pass variable to view
    $this->set(compact('products', 'counter'));
}

function cart($id=null)
 {
   $this->Product->id = $id;
   if(!$this->Product->exists())
      {
         throw new NotFoundException(__('Invalid product'));
      }

    $productsInCart = $this->Session->read('Cart');
    //pr($productsInCart);die;

    $amount=count($productsInCart);  
    $this->Session->write('Cart.' . $amount, $this->Product->read(null, $id));  

    $this->Session->write('Counter', $amount + 1);
    $this->Session->setFlash(__('Product added to cart'));

    $this->redirect('showcart');
  }
 function showcart()
 {
     $cart = array();

    if ($this->Session->check('Cart')) {
        $cart = $this->Session->read('Cart');
    }
    $this->set(compact('cart'));
}

and then create the view file for product and showcart functions. Kindly make changes in the terms accordingly. All the best!