CanExecuteChanged not monitored?

[Bernhard König]

Hi,

can it be that the TextBox control does not monitor the CanExecuteChanged of the bound ActionButtonCommand?

I can see that my code that decides if the command can be executed is called initially, but never again when I manually call RaiseCanExecuteChanged() on the command.

Don't find another reason why this could not work ...

Thanks,
Bernhard

[Todor]

Hi Bernhard,

Thank you for your question.

The CanExecute logic is executed everytime before the command is executed, so everytime the button is tapped the CanExecute logic should be executed. If it isn't, I would like to ask you to prepare a small application that is illustrating the issue. However, while testing I noticed that the button doesn't change its state to disabled when CanExecute returns false. This has already been fixed and you will see the change if you download our internal build that will be available for download from the Downloads section of your account later today.

Regards,
Todor
the Telerik team

[Bernhard König]

Hi Todor,

thanks for your response!

Is it really the case that the CanExecute logic is only executed when the button is tapped? This would explain my problem. In my case, the button is initially disabled correctly (by the initial call to the CanExecute logic which returns false), so it isn't possible to tap it as it's disabled now.

In my scenario I want to have the CanExecute-logic re-executed everytime the user enters something into a textbox. So in the Keypress-event of the textbox, I call the Command.RaiseCanExecuteChanged() method everytime. This should raise an event on the Command and then the RadTextBlock should execute the CanExecute logic again and enable (or disable) the button depending on the result without having the user to press the button.

I hope I explained it well ... else I could send you a small sample app of course!

Thanks,
Bernhard

[Todor]

Hi Bernard,

I'd like to let you know that the internal build is now available, so you can get it from the downloads section of your account. Now CanExecute is called everytime the CommandParameter (by default this is the text) is changed, so you won't need to call RaiseCanExecuteChanged.

Let me know if the internal build fixes your issue.

All the best,
Todor
the Telerik team

[bc3tech]

So if the parameter to ActionButtonCommand is NOT blank (eg: some other object) then how can I get the ActionButton to refresh? The object that is the parameter IS attempting to fire CanExecuteChanged but the handler is showing as 'null' which tells me it never got subscribed to.

Any hints?

[Todor]

Hello Brandon,

When the parameter is changed, the ActionButton will refresh its state depending on the value returned by the command's CanExecute method. If this doesn't work correctly on your side, please send us a sample that we can use to reproduce the issue.

Let us know if you need further assistance.

Regards,
Todor
Telerik

[bc3tech]

[quote]Todor said:Hello Brandon,

When the parameter is changed, the ActionButton will refresh its state depending on the value returned by the command's CanExecute method. If this doesn't work correctly on your side, please send us a sample that we can use to reproduce the issue.

Let us know if you need further assistance.

Regards,
Todor
Telerik

 

 

[/quote]
Sure i'll see if I can come up w/ a simple example to emulate what I was getting. If I can't then maybe it'll help me figure out what I was doing wrong at least!

I'll report back either way.

[Todor]

Great!

I'm looking forward to your reply, then.

Regards,
Todor
Telerik

[bc3tech]

Quick update; I built a very simple bare bones app emulating what I was trying to do (view, view model, command as property, data binding it all together) and the action button worked as expected. Guess i'll have to check out my other app a bit more closely!

thanks for the response