Download Source Code
This post is part of a series of blog
posts and videos about the Task-It (task management) application that I
have been building with Silverlight 4 and Telerik's RadControls for
Silverlight 4. For a full index of these resources, please go here.
One of the posts listed in the index provides a full source download
for the application.
Last week I presented a webinar called "Building a real-world application with RadControls for Silverlight 4". For those that didn't get to see the webinar, you can view it here:
Building a read-world application with RadControls for Silverlight 4
Since the webinar I've received several requests asking if I could post the source code for the simple application I showed demonstrating some of the techniques used in the development of Task-It, such as MVVM, Commands and Internationalization. This source code is now available for download above.
After downloading the source:
The last two steps are necessary only for the Tasks page to work properly (using WCF RIA Services).
Now some notes about each page:
This is not the way I recommend coding a line-of-business application in Silverlight, but simply wanted to show how the code-behind approach would look.
This page introduces MVVM and Commands. You'll notice in the XAML that the Command property of the RadMenuItem and the Button are both bound to a SaveCommand. That comes from the view model. If you look in the code- behind of the user control you'll see that an instance of a CommandViewModel is instantiated and set as the DataContext of the UserControl.There is also a listener for the view model's SaveCompleted event. When this is fired, it tells the view (UserControl) to display the MessageBox.
This sample is similar to the previous one, but instead of using hard-coded strings in the UI, the strings are obtained via binding to view model properties. The view model gets the strings from the .resx files (Strings.resx or Strings.de.resx) under Assets/Resources. If you uncomment the call to ShowGerman() in App.xaml.cs's Application_Startup method and re-run the application, you will see the UI in German. Note that this code, which sets the CurrentCulture and CurrentUICulture on the current thread to "de" (German) is for testing purposes only.
Once again, very similar to the previous example.The difference is that we are now using a RadWindow to display the 'Saved' message instead of a MessageBox. The advantage here is that we do not have to hold on to a reference to the view model in our code behind so that we can get the 'Saved' message from it. The RadWindow's DataContext is now also bound to the view model, so within its XAML we can bind directly to properties in the view model. Much nicer, and cleaner.
One other thing I introduced in this example is the use of spacer Rectangles. Rather than setting a width and/or height on the rectangles for spacing, I am now referencing a style in my ResourceDictionary called StandardSpacerStyle. I like doing this better than using margins or padding because now I have a reusable way to create space between elements, the Rectangle does not show (because I have not set its Fill color), and I can change my spacing throughout the user interface in one place if I'd like.
This page is quite a bit different than the other four. It is a very simple, stripped-down version of the Tasks page in the Task-It application. The Tasks.xaml UserControl has a ContentControl, and the Content of that control is set based on whether we are looking at the list of tasks or editing a task. So it displays one of two child UserControls, which are called List and Details. List has the RadGridView, Details has the form.
In the code-behind of the Tasks UserControl I am once again setting its DataContext to a view model class. The nice thing is, whichever child UserControl is being displayed (List or Details) inherits its DataContext from its parent control (Tasks), so I do not have to explicitly set it.
The List UserControl simply displays a RadGridView whose ItemsSource is bound to a property in the view model called Tasks, and its SelectedItem property is bound to a property in the view model called SelectedItem. The SelectedItem binding must be TwoWay so that the view is notified when the SelectedItem changes in the view model, and the view model is notified when something changes in the view (like when a user changes the Name and/or DueDate in the form).
You'll also notice that the form's TextBox and RadDatePicker are also TwoWay bound to the SelectedItem property in the view model. You can experiment with the binding by removing TwoWay and see how changes in the form do not show up in the RadGridView. So here we have an example of two different views (List and Details) that are both bound to the same view model...and actually, so is the Tasks UserControl, so it is really three views.
WCF RIA Services
By the way, I am using WCF RIA Services to retrieve data for the RadGridView and save the data when the user clicks the Save button in the form. I created a really simple ADO.NET Entity Data Model in WebinarProject.Web called DataModel.edmx. I also created a simple Domain Data Service called DataService that has methods for retrieving data, inserting, updating and deleting. However I am only using the retrieval and update methods in this sample. Note that I do not currently have any validation in place on the form, as I wanted to keep the sample as simple as possible.
Technically, I should move the calls to WCF RIA Services out of the view model and put them into a separate layer, but this works for now, and that is a topic for another day!