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Asked: 2026-05-30T10:00:09+00:00

I’m writing a WPF application while mostly adhering to the MVVM design pattern. The

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I’m writing a WPF application while mostly adhering to the MVVM design pattern. The application has various educational modules broken up into different categories to be accomplished by the user. The modules are organized into a hierarchical menu. My ViewModel has a class called MenuPageViewModel which exposes the information needed to render a MenuNode. Naturally, the terminal elements in the menu tree have content that I’d like to display to the user. This content can be one of many different types of modules. Currently, when the user selects a module in the menu, I can’t see any way around using a large conditional block to determine what type of ViewModel I’d like to return to be displayed based on the type of the MenuItem’s Content Property. For example…

if (CurrentlySelectedMenuItem.Content is Lesson)
                return new LessonViewModel(CurrentlySelectedMenuItem.Content as Lesson);
if (CurrentlySelectedMenuItem.Content is SkillsCheck)
                return new SkillsCheckViewModel(CurrentlySelectedMenuItem.Content as SkillsCheck);

Can someone give me a hint to a more elegant and maintainable approach? Right now, if I add a new module type, I have to remember to update this conditional block, and that just sort of annoys me.

Thanks.

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1 Answer

  1. Editorial Team

    If you are using Unity/Prism then using the container to resolve the object would be my first preference.

    _container.Resolve(Type.GetType(strObjectType)) as BaseViewModel;

    where strObjectType is a string with the type of class you want to create (eg “LessionViewModel” )

    if you are not using Unity, then reflection works

    Activator.CreateInstance(strObjectType) as BaseViewModel;

    with both solutions you need to have the string with the class type on your menuItem.

    A third option is to have a factory, but it would probably end up having a conditional situation within it or will contain the code i just listed.

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