public function addToCart($userId, $productId)
{
$item = ShoppingCartItems::where('shopping_cart_id', $this->id)->where('product_id', $productId)->first();
if (!$item) {
$item = new ShoppingCartItems();
$item->shopping_cart_id = $this->id;
$item->product_id = $productId;
$item->quantity = 1;
$item->save();
}
return $this->getItemCount($userId);
}
