Need additional help with binding multiple CommandParameters using MultiBinding
- by Dave
I need to have a command handler for a ToggleButton that can take multiple parameters, namely the IsChecked property of said ToggleButton, along with a constant value, which could be a string, byte, int... doesn't matter.
I found this great question on SO and followed the answer's link and read up on MultiBinding and IMultiValueConverter. It went really smoothly until I had to write the MultiBinding, when I realized that I also need to pass a constant value and couldn't do something like
<Binding Value="1" />
I then came across another similar question that Kent Boogaart answered, and then I started to think about ways that I could get around this.
One possible way is to not use MVVM and simply add the Tag property to my ToggleButton, in which case my MultiBinding would look like this:
<MultiBinding Converter="{StaticResource MyConverter}">
<MultiBinding.Bindings>
<Binding Path="IsChecked" />
<Binding Path="Tag" />
</MultiBinding.Bindings>
</MultiBinding>
Kent had made a comment along the lines of, "if you're using MVVM you should be able to get around this issue". However, I'm not sure that's an option for me, even though I have adopted MVVM as my WPF pattern of necessity choice.
The reason why I say this is that I have wayyyy more than one ToggleButton in the UserControl, and each of the ToggleButtons' Commands need to call the same function. But since they are ToggleButtons, I can't use the property bound to IsChecked in the ViewModel, because I don't know which one was last clicked. I suppose I could add another private property to keep track of this, but it seems a little silly. As far as the constant goes, I could probably get rid of this if I did the tracking idea, but not sure of any other way to get around it.
Does anyone have good suggestions for me here? :)
EDIT -- ok, so I need to update my bindings, which still don't work quite right:
<ToggleButton Tag="1" Command="{Binding MyCommand}" Style="{StaticResource PassFailToggleButtonStyle}" HorizontalContentAlignment="Center" Background="Transparent" BorderBrush="Transparent" BorderThickness="0">
<ToggleButton.CommandParameter>
<MultiBinding Converter="{StaticResource MyConverter}">
<MultiBinding.Bindings>
<Binding Path="IsChecked" RelativeSource="{RelativeSource Mode=Self}" />
<Binding Path="Tag" RelativeSource="{RelativeSource Mode=Self}" />
</MultiBinding.Bindings>
</MultiBinding>
</ToggleButton.CommandParameter>
</ToggleButton>
IsChecked was working, but not Tag. I just realized that Tag is a string... duh. It's working now! The key was to use a RelativeSource of Self.
