MVC 2: Electric Boogaloo - What's new in MVC 2

The MVC team loves their rec center, but an evil real estate developer wants to bulldoze it to build a hipster bar named Ruby's.  The team has been coding their butts off with MVC 2, but will the new features be enough to save the rec center?  Will the cynical real estate developer cackle and complain that it's still not enough?

Will the MVC team get areas right?  Will the new templated HtmlHelpers strike the right balance of rapid development and fine control?  Will validation concerns get muddled up with UI concerns?  Will more web forms developers make the switch to MVC?

New Areas

Areas are an organizing tool for large web sites.  If you've got lots of view and lots of controllers plus some shared content, areas can work as a top-level routing mechanism.

Example areas might be Admin for an administrative site, Store for a ecommerce site, etc.  They can be either folders or separate web projects.  Use the AreaRegistration class to set up your routes in your Global.asax (taken from MSDN article):

public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

    AreaRegistration.RegisterAllAreas();

    routes.MapRoute(
        "Default",                                              // Route name
        "{controller}/{action}/{id}",                           // URL with parameters
        new { controller = "Home", action = "Index", id = "" }  // Parameter defaults
    );
}

Then override AreaRegistration in the area's folder or in the root of the area web project (also taken from MSDN article):

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace Store
{
    public class Routes : AreaRegistration
    {
        public override string AreaName
        {
            get { return "Store"; }
        }

        public override void RegisterArea(AreaRegistrationContext context)
        {
            context.MapRoute(
                "Store_Default",
                "Store/{controller}/{action}/{id}",
                new { controller = "Products", action = "List", id = "" }
            );
        }
    }
}

Sharp Architecture has had areas since its first release.  I remember hearing rumors about areas coming in MVC for version 1.0, but I guess it wasn't ready.  The biggest difference between the Microsoft version and the Sharp Architecture version is that the Microsoft version lets you register different web projects.

Theoretically, multiple teams can work on multiple web projects, then these web projects can be rolled into the same solution and AreaRegistration can make them appear as one big web site to a browser.  I don't know how much of a need that is, but I guess if you have distributed teams that can't get to the same source code repository, it might be useful.  I prefer multiple folders in one web project over multiple web projects to keep build times down and Visual Studio responsiveness up.  I wouldn't break out each logical web site section to its own web project until the folder approach stopped working.

New HtmlHelpers

I'm not sure if Code Camp Server pushed the MVC team into this or just showed how it was possible to take HtmlHelpers to this extreme, but I'm glad to see the same concepts getting rolled into the base class libraries.

I think the new HtmlHelpers do give a nice range of control over your markup.  You can use:

<%= Html.LabelFor(x => x.FirstName) %>
<%= Html.EditorFor(x => x.FirstName) %>
<%= Html.LabelFor(x => x.LastName) %>
<%= Html.EditorFor(x => x.LastName) %>

if you want to be fairly explicit for each form element.  Or you can save a lot of keystrokes with:

<%= Html.EditorFor(x => x) %>

And if that's not enough, you can decorate your models with some UI hint attributes and roll your own rendering.  I think this is something large web projects will take advantage of for consistent markup and control rendering.  Seems like this has the advantages of homemade server controls without some of the hassles (INamingContainer, I'm looking at you).

New Validation

I did worry for a little bit about the UI stuff bleeding into the model with these new attributes.  Seems like we've got a leaky abstraction there.  But these days I think of the MVC model as the view model, not the domain model.  The view model is married to the view it works with.  It has no other purpose than to represent the data in that view.  Well, now it also validates the data in that view, at least initially.  Oh, and it now controls some of the view rendering.  Damn.  That's three responsibilities for my little view model.

But I don't have an alternative proposal to attribute-heavy view models either.  I don't want partial classes.  I haven't seen much benefit to the buddy class approach.  And I do want to reuse some of my UI hints across view models (like a date picker for DateTime types).  Plus, I want to take advantage of the new client and server side validation of my view model before it gets into the action method.  MVC 2 has this built in.

I guess I'll grin and bear it and work on a new blog post about the Triple Responsibility Principal for View Models (as opposed to SRP). :D

Future

I've already talked about where MVC views are now and where they are going, and the view engine is definitely getting better. I still think views will continue to be the most in-flux part of the MVC framework.  I know people that are very happy with Spark as a view engine, and Louis DeJardin, the guy who wrote Spark, is now working for Microsoft on the ASP.NET team.  I don't have any inside scoop, but I wouldn't be surprised if the web forms view engine got a little."sparkier".

Views may also be the area with the most room for improvement, depending on who you talk to.  When I visit with people about MVC and explain that runat="server" is gone and you can go ahead and close your Visual Studio toolbox, most get a glazed look.  They don't want to hand code the HTML.  They don't want to see a property sheet that doesn't know anything about their current mouse selection.  They don't want to give up their current productivity.

I get that, but I think you can be faster without the designers and toolboxes and property sheets.  It takes a while to get used to using the keyboard more than the mouse, but I think it's worth pushing yourself over that learning curve.

Time to switch from Web Forms to MVC?

I push MVC on projects where I have influence on that decision.  In your world, it's your call.  You may have environment constraints, in-flight projects, etc.

But it also doesn't have to be all or nothing.  You don't have to wait for a greenfield project to fall in your lap.  You can run MVC inside your current Web Forms project.  It's just another set of HttpHandlers living under ASP.NET.  Here is some guidance for getting your current project set up to do this.

I encourage you to give it a try and see what you think.  It will take a while to get used to the paradigm.  It's not hard - just different.  But I think once you're used to it, you'll like the separation of concerns, the easier testing, and the more natural flow for web development.

By natural flow, I mean embracing the world of GET and POST.  I mean when you need to expose JSON, an RSS feed, or something else (XML, PDF, file, etc.), Controller Actions are ready to go.  Stop writing custom HttpHandlers or fighting WCF configuration for this stuff.  It should be simpler, and it is with Controller Actions and the right ActionResult.

Make it a goal to get some real-world MVC experience in 2010.  Think of the kids on the MVC team and their beloved rec center.  Don't let their dream die.  They've come too far.  And remember the tag line from Breakin' 2 - "If you can't beat the systembreak it!".