Comments on Functional Fun: Hooking up Commands to Events in WPF

@Vishal, That's certainly one way of doing it....

2012-02-09T08:55:23.085Z

@Vishal,
That's certainly one way of doing it. These days, I tend to write all my commands using a variation on Josh Smith's RelayCommand. My take on it is here .

Hello again, got my answer by doing a little googl...

2012-02-09T05:26:10.325Z

Hello again, got my answer by doing a little googling.. View Model object needs to pass while creating the instance of 'TextChangedCommand' class.. e.g. return new TextChangedCommand(this); :-)

Hi Sam, Thank you for a really good post. I am stu...

2012-02-09T04:53:11.154Z

Hi Sam, Thank you for a really good post.
I am stumped by a problem. For example, How do I access method or properties defined in ViewModel class in the 'Execute' method of 'TextChangedCommand' class (of course without creating the new object of ViewModel class).

Kevin, The EventArgs from the event get passed thr...

2012-01-16T16:18:54.240Z

Kevin, The EventArgs from the event get passed through to the command as its parameter when it is executed.

Nice work! But how could you handle an event with ...

2012-01-16T16:04:48.860Z

Nice work!
But how could you handle an event with arguments, say TextBox.PreviewKeyUpCommand in which I need to access its argments. Is there a way to specify something like CommandParameter="..."?

I figured it out.. Very cool Idea here!!

2011-09-17T04:24:48.021+01:00

I figured it out.. Very cool Idea here!!

This is awesome but it does not work inside a Data...

2011-09-17T04:15:03.185+01:00

This is awesome but it does not work inside a DataTemplate which is where it would be most powerful. Can anyone help me figure out how to do it?

That is what is was looking for. Great example tha...

2011-05-16T15:49:04.176+01:00

That is what is was looking for. Great example that helps in complete decoupling between View and ViewModel.

Great Thanks

This is fantastic. Very useful and provides a good...

2011-05-16T15:49:03.313+01:00

This is fantastic. Very useful and provides a good way of understanding the power of dependency properties and attached properties

Thanks, great thing. WPF is not totally suited for...

2011-05-16T15:48:56.520+01:00

Thanks, great thing. WPF is not totally suited for MVVM. Such additions are great help.

Good article. Another implementation for generic s...

2011-04-20T12:38:32.933+01:00

Good article.
Another implementation for generic solution using reflection emit for emitting the event handler at runtime when you supply in XAML the event name for any control with the command binding

if i have an event (mouse click)to transfer contro...

2011-02-16T11:15:39.035Z

if i have an event (mouse click)to transfer control from one window to another , and i now have to do the same without using an event handler, how can i do this ?

That's awesome! Keep up the good work.

2011-01-20T17:20:55.006Z

That's awesome! Keep up the good work.

@Sam That's the way I already do. I just thoug...

2010-11-29T09:44:33.334Z

@Sam
That's the way I already do. I just thought that it would be more confortable to use the command-like solution.

Thanks for the post, and thanks for the answers!

@Ákos, Thanks for the clarification. I understan...

2010-11-26T11:46:55.770Z

@Ákos,
Thanks for the clarification. I understand what you're asking now.

It wouldn't be straightforward to do what you want using my Event->Command binding - and it probably wouldn't be the best way, either.

I would suggest that you create something like an IsTextBoxEnabled property on your ViewModel, make sure your ViewModel raises the appropriate PropertyChanged events, then bind the TextBox.IsEnabled directly to that property.

@Sam, For example, I have a TextBox, and I want t...

2010-11-26T11:29:34.286Z

@Sam,

For example, I have a TextBox, and I want to hook up (using your code) aCommand to TextBox.TextChanged event. (I don't want to implement ICommand, so I use Josh Smith's RelayCommand as it has all the functionalities I need.) And this way I would like to see, that when aCommand.CanExecute() == false, then aTextBox.IsEnabled == false.

Is it clear now?

Thanks!

@Ákos, I'm not sure exactly what you're ...

2010-11-26T10:51:59.689Z

@Ákos,
I'm not sure exactly what you're asking here.

When you bind a command to a Button, it automatically gets disabled when CanExecute returns false, or enabled if it returns true. One thing to make sure of, when you implement ICommand directly, is to raise the CanExecuteChanged event when CanExecute is likely to return a different value to before.

If you don't do that, the button will be enabled or disabled depending on the value returned by CanExecute at the time you bound the command to it, and it will never change.

Hope that helps.

Thanks for the post! It's really great! But I...

2010-11-26T10:31:24.628Z

Thanks for the post! It's really great!

But I have a problem. I need the service of commands which binds the commands CanExecute() value to the enability of the related control.

Do You have any idea how to improve your example to reach my goal?

Thank you very much!

Thanks, great thing. WPF is not totally suited for...

2010-08-27T22:34:37.382+01:00

Thanks, great thing. WPF is not totally suited for MVVM. Such additions are great help.

Thanks a lot for the posting..... I was struggling...

2010-08-21T06:46:55.012+01:00

Thanks a lot for the posting..... I was struggling to get it done using MVVM before.... I really appreciate it .....

VK

Ryan. Glad you like it - and thanks for putting th...

2010-02-02T16:07:36.517Z

Ryan. Glad you like it - and thanks for putting the link on your blog!

This is fantastic. Very useful and provides a good...

2010-02-02T14:43:45.085Z

This is fantastic. Very useful and provides a good way of understanding the power of dependency properties and attached properties

Eric, I think the problem is that DropDownClosed...

2009-06-13T16:16:47.172+01:00

Eric,
I think the problem is that DropDownClosed is a standard event rather than a routed event - my code is only designed to work with routed events. You would need to create a custom version of the behaviour specially for handling that event on ComboBoxes. Sorry I can't be more help than that at the moment!

Sam, This looks really promising but I ran into th...

2009-06-12T23:41:33.886+01:00

Sam,
This looks really promising but I ran into this:

public static readonly DependencyProperty DropDownClosedCommand = EventBehaviorFactory.CreateCommandExecutionEventBehavior(ComboBox.DropDownClosed, "DropDownClosedCommand", typeof(ComboBoxBehavior));

ComboBox does not expose the DropDownClosedEvent.

Any Ideas?

Thanks in advance,
Eric.

I'm now able to handle events easily by combing yo...

2009-04-24T14:53:00.000+01:00

I'm now able to handle events easily by combing your class with Josh Smith's version of MVVM.

Thanks for this post...