Should I use the Model-View-ViewModel (MVVM) pattern in Silverlight projects?

Question

One challenge with Silverlight controls is that when properties are bound to code, they\'re no longer really editable in Blend. For example, if you\'ve got a ListView that\'

Answer 1

Take a look at my article about MVVM and Silverlight in real life projects and decide for yourself.

http://alexburtsev.wordpress.com/2011/03/05/mvvm-pattern-in-silverlight-and-wpf/

Answer 2

I'm not sure if I can answer your question, but I have foudn the article below very valuable. Jonas Follesø is using ninject to switch out his services when in design/blend mode. Very nice!

http://jonas.follesoe.no/YouCardRevisitedImplementingDependencyInjectionInSilverlight.aspx

Answer 3

I also agree with Jonas regarding MVVM with Silverlight. I do believe that MVP is also a good choice, but recently I have had time to try both MVP and MVVM with Silverlight and I am much happier with the results from MVVM. (Yep, I changed my mind the more I used MVVM). The VM abstracts the binding of the Model from the View (obviously) in MVVM which allows for more binding scenarios (at least cleaner ways to do them) than with MVP. That's just one aspect, though.

I'll be posting some examples of both MVP and MVVM with Silverlight on my site.

Answer 4

I love the ViewModel pattern and highly recommend it. I have a couple of "getting started with ViewModel" types of posts on my blog.

• ViewModel Pattern
• HelloWorld.ViewModel
• Binding Converts - VisibilityConverter
• Silverlight Airlines with a ViewModel

Answer 5

I've tried a few options and I'm settling on MVVM as the best choice for me. Blendability is an important point, and I also find the VM aspect intuitive for rigging up dynamic behaviors and procedural effects and animations (like Nikhil's Silverlight.FX). At one point I tried to avoid Blend altogether through fluent interfaces but am finding the coupling between UI and behavior too painful in the long-run. I want to design my UI in Blend and then add effects and other behaviors in code, this is proving to be the best pattern for me to follow so far.

Answer 6

I definitely think you should use the MVVM pattern for Silverlight applications - and one of the benefits of the pattern is that you can actually make your application really blendable through some simple techniques. I often refer to "blendability" as "design for designability" - that you use certain techniques to make sure your application looks great in Blend.

One of the techniques - like Torbjørn points out - is to use a dependency injection framework and supply different implementations of your external services depending on wether the code is being executed in Blend or in the Browser. So I configure my container to use a dummy data provider when the code is executing in Blend, and that way you get design time support for your list boxes, data grids etc.

The challenge is often how to set the DataContext declaratively - so I often end up using a service locator class a a "front end" to the IoC container. That way I can bind the data context to a property on the service locator.

Another technique is create some kind of ObjectDataSource control (non visual) that has two properties: Design Time DataContext and RunTime Data Context. The control does the job of detecting where is being executing, and then setting the Parent DataContext to the right object.