How do I pass value to MVC3 master page ( _layout)?

Question

I have a custom modelbinder, its check the authentication cookie and return the value.

public class UserDataModelBinder<T> : IModelBinder
{
    public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {

        if (controllerContext.RequestContext.HttpContext.Request.IsAuthenticated)
        {
            var cookie =
                controllerContext.RequestContext.HttpContext.Request.Cookies[FormsAuthentication.FormsCookieName];

            if (cookie == null)
                return null;

            var decrypted = FormsAuthentication.Decrypt(cookie.Value);

            if (!string.IsNullOrWhiteSpace(decrypted.UserData))
                return JsonSerializer.DeserializeFromString<T>(decrypted.UserData);
        }

        return null;
    }
}

if I need to use it, I just need to pass it to the action. everything works.

public ActionResult Index(UserData userData)
{
    AccountLoginWidgetVM model = new AccountLoginWidgetVM();
    if (null != userData)
        model.UserData = userData;

    return View(userData);
}

However, I want to use it in my master page, because once user login, i want to display their info on the top on every page. I tried a few things, coudln't get it work

 @Html.RenderPartial("LoginPartial", ???model here??)  

Answer 1

We did it as follows:

1. Defined separate viewmodel for masterpages.

   public class MasterPageViewModel
   {
       public Guid CurrentUserId { get; set; }
       public string CurrentUserFullName { get; set; }
   }
   

2. Added injection filter and filter provider.

   public class MasterPageViewModelInjectorFilterProvider: IFilterProvider
   {
       public IEnumerable<Filter> GetFilters(ControllerContext controllerContext, ActionDescriptor actionDescriptor)
       {
           return new [] {new Filter(new MasterPageViewModelInjectorFilter(), FilterScope.Action, null), };
       }
   
       private class MasterPageViewModelInjectorFilter: IResultFilter
       {
           public void OnResultExecuting(ResultExecutingContext filterContext)
           {
               var viewResult = filterContext.Result as ViewResult;
               if (viewResult == null)
                   return;
   
               if (viewResult.ViewBag.MasterPageViewModel != null)
                   return;
   
               //setup model whichever way you want
               var viewModel = new MasterPageViewModel();
               //inject model into ViewBag
               viewResult.ViewBag.MasterPageViewModel = viewModel;
           }
   
           public void OnResultExecuted(ResultExecutedContext filterContext)
           {
           }
       }
   }
   

3. Configure filter provider:

   //in Application_Start
   FilterProviders.Providers.Add(new MasterPageViewModelInjectorFilterProvider());
   

4. Use in master:

   ViewBag.MasterPageViewModel
   

This way you have fine uncoupled architecture. Of course you can combine it with Dependency Injection (we do, but I left it out for clarity) and configure your action filter for every action whichever way you want.

Answer 2

In this case you can use ViewBag.

public ActionResult Index(UserData userData)
{
    AccountLoginWidgetVM model = new AccountLoginWidgetVM();
    if (null != userData)
        model.UserData = userData;

    ViewBag.UserData = userData;
    return View(userData);
}


@Html.RenderPartial("LoginPartial", ViewBag.UserData)

You have to make sure that userData is not null. If it'll be null the passed model will be default model of the view.