Command canexecute not updating

In the first example, we implemented a Can Execute event that simply returned true, so that the button would be available all the time.

command canexecute not updating-81

Dealing with commands is pretty straight forward, but does involve a bit extra markup and code.

The reward is especially obvious when you need to invoke the same action from multiple places though, or when you use built-in commands that WPF can handle completely for you, as we saw in the last example.

A thing to notice is that this command has a default keyboard shortcut defined, which you get as an added bonus.

Instead of clicking the button, you can try to press Ctrl N on your keyboard - the result is the same.

The visual interface consists of a single button, which we attach the command to using the Command property. The Can Execute handler, which WPF will call when the application is idle to see if the specific command is currently available, is very simple for this example, as we want this particular command to be available all the time.

This is done by setting the Can Execute property of the event arguments to true.When using the Relay Command class, a command class used for MVVM development, you may find times when a button that is enabled or disabled based on Relay Command.Can Execute does not refresh until a keyboard or mouse click.In fact, we could have avoided all of the Code-behind in the previous example, because a WPF Text Box can automatically handle common commands like Cut, Copy, Paste, Undo and Redo.WPF does this by handling the Executed and Can Execute events for you, when a text input control like the Text Box has focus.The first button will cut to the clipboard and the second one will paste from it.

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