Could somebody explain ASP.NET MVC to me?

Question

I'm trying to get into MVC and currently reading the wrox professional ASP.NET MVC book.

I kind of get it so far. Instead of each URL going to a page it goes to a controller. The controller action then gets the data and decides what view to use.

I also understand that if I have a url like/product.aspx?id=100 then the controller would get the product details and merge them with the "show product" view.

Now here's the bit I don't get...

If my product page has other stuff on it, like a login box, a "top 10 products" section, list of categories etc. which may or not be used on other pages too then how would I include them and keep their code separate?

In the classic aspx model it would be simple. If my top 10 products appeared on every page then I would put it in a master page, but more likely I would make it into a user control if it was going to be used on some pages not others.

From what I understand of MVC so far, my products controller would have to get the top 10 products and so would any other controller that was producing a page with the top 10 products on it.

Confused. Please help.

Answer 1

From what I understand of MVC so far, my products controller would have to get the top 10 products and so would any other controller that was producing a page with the top 10 products on it.

Not necessarily. You can use Master pages with MVC, as well as Partials to compartmentalize re-usable view content.

This is a good article on using Partials. http://jeffreypalermo.com/blog/asp-net-mvc-and-the-templated-partial-view-death-to-ascx/

Also, in your Top 10 products example, you could have that rendered by a child action:

[ChildActionOnly]
public ActionResult GetTopTenProducts() 
{
    var products = db.GetTopProducts(10);
    return View(products);
}

You would then have a partial view (.ascx) called "GetTopProducts.ascx" that would be rendered when you call the GetTopTenProducts() action. Then in your Master page, or anywhere you wanted that Top 10 list to show up, you would call it like this:

<% Html.RenderAction("GetTopTenProducts") %>

Answer 2

You're close.

You're just forgetting that your controller is a class that can inherit from a base class.

You can create a base controller class that handles retrieving the top ten products, and then have any controllers that need that functionality inherit from the base class.

You then create a Master Page that uses a Partial View to render the top ten products passed to the View (from the base controller).

...and voila! No code repetition.

Answer 3

Please don't forget that in ASP.NET MVC you still can use MasterPage. With specific to ASP.NET MVC 2 you can display those 10 products using RenderAction which can render Action from any Controller you select.

In addition to that, you should get to know PartialView as well.

Answer 4

You can use master pages and in MVC partial views are synonymous with user controls. The difference being master page does not have a corresponding controller. You an solve with one of two ways.

1. When you use a partial view you can pass a model in.

   <%= Html.RenderPartial("PartialView",Model) %>
   

2. You can just do the work in the partial view, utilizing the code brackets <% %>.