SL ItemsControl, command on ViewModel not firing from ItemsControl (CheckBox)

Question

I'm using PRISM v2, CAL, SL4 and MVVM and have a delegate command on my ViewModel called CheckCommand. The ItemsControl contains a checkbox and I'm trying to get the items in ItemsControl/Checkbox to fire this command when it's checked - but it's not communication back to the viewmodel!

I think it's because each items 'datacontext' is the individual object the item is bound to, rather than the ViewModel?
- My suspicion is actually correct, cause if I move my DelegateCommand out of the viewmodel and into the class defining the items in itemscontrol I can see the commands/methods beeing fired!

View:

<ListBox x:Name="BasketListBox" ItemsSource="{Binding BasketCollection}" MinWidth="200">
<ListBox.ItemTemplate>
    <DataTemplate>
        <CheckBox commands:Checked.Command="{Binding CheckCommand}"  IsChecked="False" </CheckBox>
    </DataTemplate>       
</ListBox.ItemTemplate>

Can anyone point me in the right direction please?

Cheers, Mcad.

EDIT 1:

The commanding now works, see solution below. BUT, I now run into another problem:
"An exception occurred while creating a region with name 'basketRegion'. The exception was: System.InvalidOperationException: ItemsControl's ItemsSource property is not empty. This control is being associated with a region, but the control is already bound to something else. If you did not explicitly set the control's ItemSource property, this exception may be caused by a change in the value of the inherited RegionManager attached property"

Created seperate question for this problem to make it more clean:

PRISM-MVVM, ItemsControl problem with View injection

This is one of the major limitations of the command pattern. The only way I've been able to get around it is I wrote a custom behavior that similar to the Prism behavior for commanding but it has an option to specify a string name of a command instead of a binding and then it searches up the VisualTree to the ItemsControl and uses its DataContext for binding. — Stephan
– Stephan, Commented Oct 21, 2010 at 16:14

Kent Boogaart · Accepted Answer · 2011-09-28 00:22:10Z

1

You want every CheckBox to fire the same command? You could:

<CheckBox commands:Checked.Command="{Binding DataContext.CheckCommand, ElementName=BasketListBox}"

Or you could have every child view model expose the command via their own property.

edited Sep 28, 2011 at 0:22

user142162

answered Oct 21, 2010 at 18:54

Kent Boogaart

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3 Comments

Mcad001 Over a year ago

My post below every now and then gives me the following error while running my code: An exception occurred while creating a region with name 'basketRegion'. The exception was: System.InvalidOperationException: ItemsControl's ItemsSource property is not empty. This control is being associated with a region, but the control is already bound to something else. If you did not explicitly set the control's ItemSource property, this exception may be caused by a change in the value of the inherited RegionManager attached property.

Mcad001 Over a year ago

I guess the problem is that I both bind the ItemsSource of the listbox to basketcollection and then I bind "{Binding DataContext.CheckCommand, ElementName=basketListBox}"... But If I remove the ItemsSource I cannot populate my Listbox, any idea how to solve this?

Mcad001 Over a year ago

Created seperate question for this problem to make it more clean: stackoverflow.com/questions/4022303/…

Mcad001 · Accepted Answer · 2010-10-25 07:25:15Z

0

Thanx Kent. You put me on the right path to solve this, ended up doing this:

<ListBox x:Name="basketListBox" ItemsSource="{Binding basketcollection}" MinWidth="200">
<ListBox.ItemTemplate>
<DataTemplate>
        <CheckBox commands:Checked1.Command="{Binding DataContext.CheckCommand, ElementName=basketListBox}" Content="{Binding basketName}">             </CheckBox>
    </DataTemplate>       
</ListBox.ItemTemplate>

answered Oct 25, 2010 at 7:25

Mcad001

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