Wpf command canexecute not updating
Like with all separated presentation patterns, the key to using the MVVM pattern effectively lies in understanding the appropriate way to factor your application's code into the correct classes, and in understanding the ways in which these classes interact in various scenarios.The following sections describe the responsibilities and characteristics of each of the classes in the MVVM pattern.Weak Reference is harder to understand than normal, strong reference; delegate is harder than reference and Weak Delegate is the hardest of all.But if you implement Can Execute Changed event in other way – you have a problem.It can also greatly improve code re-use opportunities and allows developers and UI designers to more easily collaborate when developing their respective parts of the application.
The Prism Library also provides features that can help you implement the pattern in your own applications.
It is precise action that should be done when user clicked a button, tapped a list or something alike. Invalidate Requery Suggested() method, but with updating of all commands in your app! I have also some examples that led to long-and-painful debug sessions but unfortunately can’t disclose them for legal reasons.
So, common approach is to implement ICommand interface and Command Manager for Can Execute Changed event implementation like below: Well, this approach has its downsides. If you have some external source of information, e.g. And it would be too much work to rewrite some part just to make a demo…
In the MVVM pattern, the view encapsulates the UI and any UI logic, the view model encapsulates presentation logic and state, and the model encapsulates business logic and data.
The view interacts with the view model through data binding, commands, and change notification events.