public IActionResult RaisePurchaseOrder(string supplier)
 {
     if (supplier == null)
     {
         supplier = HttpContext.Session.GetString("supplier");
     }
     invService.CreatePurchaseOrder(HttpContext.Session.GetString("userId"), supplier);
     HttpContext.Session.Remove("supplier");
     return(RedirectToAction("ViewAllPurchaseOrders"));
 }