Tag Archives: model-view-viewmodel

French article about MVVM posted !

WPF, , , ,

It’s finally online after a long work.I hope my french readers will enjoy it:  http://japf.developpez.com/tutoriels/dotnet/mvvm-pour-des-applications-wpf-bien-architecturees-et-testables/

Here is the abstract translated to english:

“Inch by inch, the WPF technology is being adopted by .Net developers as a development platform for next generation user interfaces. This changeover is taking time and complicated because WPF changes principles that are well known until now in the process of designing a user interface. The Model-View-ViewModel methodology helps formalize WPF developement by giving guidance that leads to apps cleary architectured, testable, and by optimizing the workflow between developer and designer.”

Very simple MVVM demo application

WPF, , , ,

The last couple of days, I’ve been busy writing an article about MVVM in French. I don’t know yet if I’ll translate it to English, but I’m sure I can share the demo application, and this is the goal of this post !

I think the best way to understand how things fit together is to explore the source code of the application.

It’s a very small demo because I wanted to demonstrate only a subset of MVVM facilities, so you’ll find:

  • an easy way to work with commands in MVVM using Josh Smith RelayCommand class
  • the power of the ICollectionView interface to implement navigation and search feature
  • empty code-behind file for my views
  • a base class for all my ViewModel objects (again, based on the work of Josh)

mvvm-demo-1

mvvm-demo-2

You can download the source code here. Enjoy 🙂

Model-View-ViewModel, Commands and InputBindings

WPF, ,

Article updated ! I find out that the Command property of the KeyBinding class is not a DependencyProperty… This prevent using the syntax I wanted (binding to an ICommand exposed in the ViewModel). There are several workarounds you can find across the web (using a MarkupExtension, an attached properies…) but because I didn’t have much time, I finally put some glue in my code-behind ;(

I’m still playing with MVVM those days and today, I needed a simple behavior I didn’t know how to do with MVVM. I finally found a simple solution and as I love them, it’s 100% XAML :p

The problem is simple, I have a ListBox where the user can type date in it.
When the User Validate his input, I need to process the text entered and return another value.
The User can validate the input by pressing the Enter key while the TextBox has the focus.

My first attempt was the subscribe to the KeyUp event, and in the code-behind, delegate the work to the associated ViewModel class. I don’t like that solution a lot (events handler in code-behind are sort of ugly…).

I know I could define an ICommand in my ViewModel and do the work directly there (using the excellent RelayCommand class written by Josh Smith). The problem was how to trigger this command when the Enter key is pressed. well, actually it’s pretty simple:

As I updated the article (because Command is not a DP), I finally did the same thing in C# in the code-behind…