Question

I am passing some viewdata and view bag to the view through controller , below is the snippet of the code:

IProductRepository prodResp = new ProductRepository();
        Product getGarages = prodResp.GetDetailsForGarages((int)Session["EventID"]);
        Product getHelmets = prodResp.GetDetailsForHelmet((int)Session["EventID"]);
        if (getGarages == null)
        {

            ViewBag.Garages = null;
        }
            ViewBag.Garages = getGarages;
            int totalGarages = getGarages.QtyAvailable;
            var garages = Enumerable.Range(1, totalGarages).Select(x => new SelectListItem { Value = x.ToString(), Text = x.ToString() });
            ViewBag.GaragesDropDown = new SelectList(garages.ToList(), "Value", "Text");

            if (getHelmets == null)
            {
                ViewBag.helmets = null;
            }
            ViewBag.helmets = getHelmets;
        return View(booking);
    }

View

<% if (Convert.ToBoolean(ViewBag.boolSecondDriver))
                      {%>

                    <lable>Second Driver Availablity For this Event</lable><br />
                   <lable>Secondriver:</lable> <%: Html.TextBox("SecondDriver") %>
                    <br />
                   <lable>SecondriverPrice:</lable> <%: ViewBag.trackday.SecondDriverPrice %>
                    <br /><br />

                    <lable>Number of Helmets Available For this Event</lable><br /><br />
                    <lable>No of Helmets:</lable><%: ViewBag.helmets.QtyAvailable%><br />
                    <lable>Price per unit:</lable><%: ViewBag.helmets.UnitCost%> <br /><br />

                    <lable>Number of Garages Available For this Event</lable><br /><br />
                   <lable>No of Garages:</lable> <%: ViewBag.Garages.QtyAvailable%><br />
                    <lable>price per unit:</lable><%: ViewBag.Garages.UnitCost%>

                     <%}
                       else{ %> 


                      <lable>Second Driver Availablity For this Event</lable><br />
                   <lable>Free</lable>

                    <br /><br />

                    <lable>Number of Helmets Available For this Event</lable><br /><br />
                    <lable>No of Helmets:</lable><%: ViewBag.helmets.QtyAvailable%><br />
                    <lable>Price per unit:</lable><%: ViewBag.helmets.UnitCost%> <br /><br />

                    <lable>Number of Garages Available For this Event</lable><br /><br />
                   <lable>No of Garages:</lable> <%: ViewBag.Garages.QtyAvailable%><br />
                    <lable>price per unit:</lable><%: ViewBag.Garages.UnitCost%>

                      <%} %> 

The issue I am having is I cant hide or unhide the Viewbag if the value of viewbag.value is null then the respected viewbag.values should be hidden in the view , therefore I am getting errors: Cannot perform runtime binding on a null reference. Any suggestions or alternatives will be highly appreciated thanx.

Answer 1

Any suggestions or alternatives will be highly appreciated thanx.

Have you considered using a ViewModel?

ViewBag is fine when dealing with single fields etc that don’t warrant a “model”, but you have a lot of code there, i see nouns like Helmet and Garage – so you should be using a ViewModel.

Then you can use:

<%: Html.DisplayFor(model => model.SecondDriver) %>

And if SecondDriver is null nothing will be rendered.

And you can create a display template for whatever type SecondDriver is, and move the markup there, meaning you can re-use it across any Views.

Don’t know about you, but when i do MVC development, my #1 goal is to keep my View clean and free from code soup – which is what you currently have.