digitalMoto.net

I am using the M-V-VM pattern on a WPF app. The rules that we are following on my team state that the View only knows about the ViewModel via the DataContext. The ViewModel has no explicit knowledge of the View.

BTW: I created the project using the WPF M-V-VM template available on CodePlex (I think?). It already contains the DelegateCommand classes.

I have an “OK” button.

In WPF, a button does nothing. If you want to do do “something” you have to wire up a command that resides in the ViewModel.

View:

<Button Command="{Binding UserClickedOkButtonCommand}" Content="OK" />

ViewModel:

public ICommand UserClickedOkButtonCommand { get { return new DelegateCommand( UserClickedOkButton); } }

public void UserClickedOkButton()
{
// do something
}

If you put a break point on the UserClickedOkButton, you will see the event is correctly mapped to the delegate method. So how do I close the View?

It takes a couple extra steps to get all of your ducks in a row.

First, add an x:Name=”ThisWindowName” to your View header.
Second, add a command parameter that refers back to your new window name.
Third, update the Command in the ViewModel to use a Window as it’s argument.
Fourth, use the input window argument to close the window.

Here’s the code.

View:

<Window
	...
	x:Name="ThisWindowName"
>
...
<Button Command="{Binding UserClickedOkButtonCommand}" CommandParameter="{Binding ElementName=ThisWindowName, Path=.}" Content="OK" />

ViewModel:

public ICommand UserClickedOkButtonCommand { get { return new DelegateCommand( UserClickedOkButton); } }

public void UserClickedOkButton(Window window)
{
	// Do Something
	window.Close();
}

The window is closed. Concerns are separated. MVVM rules are followed.

Works on my machine.