Passing data to Master Page in ASP.NET MVC


Question

What is your way of passing data to Master Page (using ASP.NET MVC) without breaking MVC rules?

Personally, I prefer to code abstract controller (base controller) or base class which is passed to all views.

1
102
9/17/2008 12:08:39 AM

Accepted Answer

If you prefer your views to have strongly typed view data classes this might work for you. Other solutions are probably more correct but this is a nice balance between design and practicality IMHO.

The master page takes a strongly typed view data class containing only information relevant to it:

public class MasterViewData
{
    public ICollection<string> Navigation { get; set; }
}

Each view using that master page takes a strongly typed view data class containing its information and deriving from the master pages view data:

public class IndexViewData : MasterViewData
{
    public string Name { get; set; }
    public float Price { get; set; }
}

Since I don't want individual controllers to know anything about putting together the master pages data I encapsulate that logic into a factory which is passed to each controller:

public interface IViewDataFactory
{
    T Create<T>()
        where T : MasterViewData, new()
}

public class ProductController : Controller
{
    public ProductController(IViewDataFactory viewDataFactory)
    ...

    public ActionResult Index()
    {
        var viewData = viewDataFactory.Create<ProductViewData>();

        viewData.Name = "My product";
        viewData.Price = 9.95;

        return View("Index", viewData);
    }
}

Inheritance matches the master to view relationship well but when it comes to rendering partials / user controls I will compose their view data into the pages view data, e.g.

public class IndexViewData : MasterViewData
{
    public string Name { get; set; }
    public float Price { get; set; }
    public SubViewData SubViewData { get; set; }
}

<% Html.RenderPartial("Sub", Model.SubViewData); %>

This is example code only and is not intended to compile as is. Designed for ASP.Net MVC 1.0.

77
4/14/2009 1:33:07 AM

I prefer breaking off the data-driven pieces of the master view into partials and rendering them using Html.RenderAction. This has several distinct advantages over the popular view model inheritance approach:

  1. Master view data is completely decoupled from "regular" view models. This is composition over inheritance and results in a more loosely coupled system that's easier to change.
  2. Master view models are built up by a completely separate controller action. "Regular" actions don't need to worry about this, and there's no need for a view data factory, which seems overly complicated for my tastes.
  3. If you happen to use a tool like AutoMapper to map your domain to your view models, you'll find it easier to configure because your view models will more closely resemble your domain models when they don't inherit master view data.
  4. With separate action methods for master data, you can easily apply output caching to certain regions of the page. Typically master views contain data that changes less frequently than the main page content.

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