EventToCommand + DataStateBehavior eases MVVM pain


MVVM is a pattern.  There are all sorts of MVVM frameworks popping up that help make implementing the pattern easier.  If you select the MVVM tag off of www.codeplex.com, you will find a number of them:


One I have recently grown fond of is http://mvvmlight.codeplex.com/.  The reason I like this one is because they have built an Expression Blend Behavior called EventToCommand.  Details for the behavior:


As the post says, ‘EventToCommand is used to bind an event to an ICommand directly in XAML.”

This is WAY COOL!!!  EventToCommand helps overcome commanding challenges in Silverlight.

I love Blend Behaviors.  If you haven’t looked into them, YOU MUST!  Every WPF and Silverlight developer should be using them (where applicable).  “A Behavior is in essence a reusable piece of interactivity that can be applied directly to user interface elements…”

Here are some resources:

Good Overviewhttp://tinyurl.com/BehaviorsOverview

More readinghttp://tinyurl.com/BehaviorsTriggersActions

Expression Blend 3 SDKhttp://tinyurl.com/blend3sdk 

Lots of folks creating and uploading them to Expression Galleryhttp://tinyurl.com/BehaviorsGallery

Behaviors from the Blend Teamhttp://expressionblend.codeplex.com/

Behaviors are part of the Blend SDK.  There is a lot of confusion about the Blend SDK because people think you have to buy Blend to use it.  You don’t!  You can download it from http://tinyurl.com/blend3sdk and use it straight from Visual Studio.  Blend definitely makes wiring up Behaviors easier so you should it for that if you are already using Blend!

The samples you can download from http://expressionblend.codeplex.com/ include DataStateBehavior and DataStateSwitchBehavior.  Peter Blois has a good post on these behaviors:


DataStateBehavior/DataStateSwitchBehavior provide a nice clean way to change values in your ViewModel that result in initiating animations in your View.

I’ve been wanting to whip up a simple sample that shows both EventToCommand and DataStateBehavior/DataStateSwitchBehavior.  Unfortunately, I don’t have the time right now to do so.  Instead of sitting on this, I decided to blog about it first, then share a sample/video when I get around to it.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s