DM-V-VM part 7: Encapsulating commands

WPF Patterns

Bryant Likes's Blog — Wed, 27 Sep 2006 23:31:16 GMT

If you're doing WPF development, you really need to check out Dan Crevier 's series on DataModel-View-ViewModel.

DataModel-View-ViewModel pattern series

Dan Crevier's Blog — Thu, 12 Oct 2006 05:00:57 GMT

I thought I should add a post with the full list of posts in the D-V-VM pattern. They are: DataModel-View-ViewModel

re: DM-V-VM part 7: Encapsulating commands

makutaku — Wed, 25 Oct 2006 01:28:24 GMT

Unfortunately this technique doesn't allow me to set multiple bindings in XAML because I can't do something such as:

<Grid

local:CreateCommandBinding.Command="{Binding MyCommand1}"

local:CreateCommandBinding.Command="{Binding MyCommand2}"

Any idea how could set multiple bindings for the command models in XAML?

re: DM-V-VM part 7: Encapsulating commands

dancre — Wed, 25 Oct 2006 06:07:11 GMT

You'll need to modify CreateCommandBinding.OnCommandInvalidated to not clear the binding. To really do it right, you'll need to remove the old command binding when the command changes.

re: DM-V-VM part 7: Encapsulating commands

makutaku — Fri, 27 Oct 2006 19:47:36 GMT

If I remove the old command binding when the command changes then, using my example above, MyCommand2 binding will remove MyCommand1 binding.

If I want to have multiple simultaneous bindings then I guess I just have to not clear the binding. I'll try that.

re: DM-V-VM part 7: Encapsulating commands

makutaku — Fri, 27 Oct 2006 20:17:33 GMT

Unfortunately I can't have two simultaneous bindings using XAML:

<Grid

local:CreateCommandBinding.Command="{Binding MyCommand1}"

local:CreateCommandBinding.Command="{Binding MyCommand2}"

because I got an error saying:

Error 54 ''p:CommandBindingCreator.Command' is a duplicate attribute name. Line 17, position 3.' XML is not valid.

The only way I found to do that was to create another attached property called Commands which takes a collection of CommandModels.

re: DM-V-VM part 7: Encapsulating commands

dancre — Tue, 31 Oct 2006 06:02:27 GMT

Sorry, I wasn't clear on the clearing. I meant you should remove e.OldValue from the binding in the property changed handler.

To handle multiple bindings, you could also allow CreateCommandBinding take a IEnumerable<CommandModel> and expose a list from the model.

COMMANDS

WPF Client Development — Tue, 05 Aug 2008 23:09:06 GMT

If you are trying to write an application in WPF that separates the UI from the underlying business logic