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Asked: 2026-05-11T10:05:16+00:00

I have two WPF list boxes. One is a list of lists (actually a

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I have two WPF list boxes. One is a list of lists (actually a List of ObservableCollection), the other is a list of all known instances of ‘Thingy’.

Here’s the datatemplate I’m using for the ‘thingy’ class. 

<DataTemplate DataType='{x:Type Model:Thingy}'>     <StackPanel Orientation='Horizontal'>         <CheckBox x:Name='ThingyInListCheckBox' Click='ThingyInList_Click'></CheckBox>         <TextBlock Text='{Binding Path=ThingyName}'></TextBlock>      </StackPanel>

Here’s the XAML for the list boxes: 

<ListBox     Name='ListOfGroups'    SelectionMode='Single'>            </ListBox> <ListBox     Name='ListOfThingys'    SelectionMode='Single'> </ListBox>

I have the data binding for the list boxes set up in code, because I’m too tired to figure out how to do it in XAML: 

ListOfGroups.ItemsSource = InMemoryCache.ThingyGroups; ListOfThingys.ItemsSource = InMemoryCache.Thingys;

What I want is the checkbox ‘ThingyInListCheckBox’ to be checked if the ‘thingy’ object is in the list that is the selected item in the ‘ListOfGroups’ listbox. So basically I need to bind it to the ‘Contains’ method of the ‘ListOfGroups’.SelectedItem while passing it the ‘ListOfThingys’.SelectedItem as a parameter.

I’m tempted to do this all in code, but I’m trying to get a better understanding of XAML data binding because I hate myself and I want me to suffer.

Is this even possible, or have I hit the inevitable ‘wall of databinding’ that exists in every other data binding system in the history of software development?

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  1. It is possible, in fact the hard thing is that there are many ways to do this and you have to choose one. None of them is a simple addition to your current code. However there is one way, by which you gain more than solving your problem. Actually, it is more of a pattern, called MVVM (some might argue about the naming).

    Here is a small explanation on your example. Suppose ThingyGroup has an IsSelected property, which is bound to the IsSelected property of the containing ListBoxItem. Again, suppose Thingy has a Group property too. Then you can use Group.IsSelected as a path to bind checkbox. Notice that there is still a small issue that IsSelected is a bool and IsChecked is a nullable bool.

    A search on MVVM should give you concrete samples.

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