Async Commands (and Async Relay Command) - EASY WPF (.NET CORE) 

Thanks Lucky, glad to hear you're sharing this content with others!

Thanks Dion, just happy to be helping the subscribers and viewers that I have!

Hey Fuzzy, I definitely have plans for this. I originally wanted my "Full Stack WPF MVVM" playlist to satisfy this need, but that series has become a bit too long. A quick crash course would be great. Thanks for the suggestion!

Hey chaw chaw, sounds like an interesting use case. I'm interested in doing some videos on more specific WPF controls, so this would be a good topic to go over. Also, for performance issues, you might want to check out UI virtualization: docs.microsoft.com/en-us/dotnet/framework/wpf/advanced/optimizing-performance-controls I've used this in production software and it makes a big difference. It's also easy to setup (just toggle an attached property on the DataGrid, magic) Thanks for the suggestion!

Hey Mihai, that's a great question and exception handling is super important. I'll add that to my list of things to do. Ironically, you commented on a pretty relative video, haha. I typically handle exceptions inside of my commands. This allows me to catch the exception, investigate it, and then set some kind of error message on the view model to notify the view. Of course, it's never a bad idea to catch/re-throw inside of a library for logging purposes, but at the end of the day I like my exceptions to funnel up to my view models/commands so that I can notify the user through the UI. Hopefully that helps a little bit, thanks Mihai!

Greetings Anonym, glad you're enjoying :)

Thanks omostan! 🚀

Thanks C T! I usually just make CanExecute virtual and override it in base classes. I think this is the simplest and most efficient way.

Thanks Kuldeep! A tutorial on MVVM popups is on the way. Navigation is the most requested topic I've received, and honestly it's probably the one thing in WPF I've run into the most issues with in the past. Definitely a good video topic!

i found what i missed sorry your code work perfectly

Thanks Wahid! I do not have any videos on CancellationTokens yet, but that is a great suggestion. Perhaps I could show off an AsyncCommand with a CancellationToken as well.

@@SingletonSean i didn't see this till i already posted but yes yes yes..if you are ever near MI all the beer or whatever you want is on me

Hey David, I think UWP is great for building Windows apps for the Windows Store and for the platforms that UWP supports. However, since WPF came before UWP, I just haven't checked out UWP yet because I feel WPF is strong enough for desktop development. I think other developers have similar feelings, hence why UWP hasn't gained as much traction yet. I am interested in checking out UWP though, so perhaps in the future! Considering the UI is XAML based, I can't imagine it is difficult to adjust from WPF. I've recently been doing a lot of Xamarin, which is also XAML based, and have noticed many similarities compared to WPF. In fact, it's easier in some cases! Hopefully UWP XAML is similar.

Good point, veroqtno. I am familiar with Stephen Cleary's (and other great developer's) async wisdom. However, async void event handlers are acceptable, and a command is similar to an event handler since we're handling button clicks (although it is not syntactically similar, but same concept). We can try and dance around async void as much as we want, but an async void is required for event handlers.

Thank you! Your videos are great please keep up with the great work! I like to see more from WPF MVVM

Hey semen, I think there is nothing wrong with this approach. The only thing to consider is exception handling, where in this case the only option is for MyCommandRealization to never throw exceptions. I think that is a valid requirement. The only other issue could be unit testing. If MyCommandRealization is private, then the only way to test the method is to execute the command. With the default RelayCommand, we don't have access to an ExecuteAsync that we can await, so it would be difficult to assert unit test results since MyCommandRealization could still be executing while we are asserting. Of course in a unit test, everything should be nearly synchronous (mocking API/database calls, etc.), so I'm not sure how large of an issue this is.

No worries Andrew, hope this helps :) docs.microsoft.com/en-us/dotnet/api/system.windows.threading.dispatcher.invoke?view=net-5.0

@@SingletonSean So I'm going to try and get the results of a request and then update the collection via the result, does that sound right?

@@SingletonSean Yup, that worked!

That's great news! I've run into that quirk quite a lot with ObservableCollections and ICollectionView.

Hey Göthâkar, I've seen some RU-vidrs add effects like this in the past, but I didn't really think it added much value. I also have limited experience in video editing. However, this comment inspired me to spend some time with practicing video editing today, and I actually think the zoom is a LOT nicer for visibility (maybe I just didn't like it before because I had never tried, haha). Turns out video editing is pretty fun. Thanks for the suggestion Göthâkar, I'm excited to add this to videos in the future and improve the quality of my videos!