Determining out the correct property return type for a data binding when using MVVM Light in a C#/WPF app?

Question

I have a C# Windows Phone 7.1 project that uses the MVVM Light toolkit. On one application page in the app I have a Telerik data bound list box that is bound to a property in my view model. At first that property had a return type of:

List<string>

With that return type the property did not show up in the list of candidate elements in the Path list box, when I activated the Create Data Binding dialog box in order to assign the list box's ItemsSource property. However, when I changed that property's return type to:

ObservableCollection<string>

it showed up immediately. In the future, how can I determine the correct return type for a particular control's ItemsSource or other data bindable property?

Answer 1

Your question is little confusing. Both are completely okay and work well for different scenarios. You use list<string> when you don't plan to change collection, and ObservableCollection otherwise.

Now, you can use MSDN(see ItemsSource property to see what property needs to be what. As you can see from documentation, ItemsSorce has to be IEnumerable, meaning all types that derive from it, can be used.

Now as for the real question, why didn't your property show up in the IDE, I can only guess that Microsoft wants you to use ObservableCollection always, but I don't agree with this. So that's why it's best to manually do the bindings to properties through Xaml.