Binding nested ItemsControls to nested collections

Question

I am trying to show pages in my WPF/Caliburn Micro application. The pages should be presented in a rectangular way to the user. My idea is to use a collection (the rows) of collections (the columns) of my base view model for the pages:

public BindableCollection<BindableCollection<BaseViewModel>> Children { get; set; }

And do something like this in the associated View:

    <ItemsControl x:Name="Children">
      <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
          <StackPanel Orientation="Vertical" />
        </ItemsPanelTemplate>
      </ItemsControl.ItemsPanel>
      <ItemsControl.ItemTemplate>
        <DataTemplate>
          <ItemsControl ItemsSource="{Binding /}">
            <ItemsPanelTemplate>
              <StackPanel Orientation="Horizontal"/>
            </ItemsPanelTemplate>
          </ItemsControl>
        </DataTemplate>
      </ItemsControl.ItemTemplate>
    </ItemsControl>

And this is wrong - I don't get what to put into the inner ItemsControl.

Thanks for any idea!

Solution

I am still not sure whether this is the perfect solution, but it works and seems not too hacky to me:

            <ItemsControl x:Name="Children">
                <ItemsControl.ItemsPanel>
                    <ItemsPanelTemplate>
                        <StackPanel Orientation="Vertical" />
                    </ItemsPanelTemplate>
                </ItemsControl.ItemsPanel>
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <ItemsControl ItemsSource="{Binding}">
                            <ItemsControl.ItemsPanel>
                                <ItemsPanelTemplate>
                                    <StackPanel Orientation="Horizontal" />
                                </ItemsPanelTemplate>
                            </ItemsControl.ItemsPanel>
                            <ItemsControl.ItemTemplate>
                                <DataTemplate>
                                    <ContentControl cal:View.Model="{Binding}" />
                                </DataTemplate>
                            </ItemsControl.ItemTemplate>
                        </ItemsControl>
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ItemsControl>

Answer 1

A forward slash in a Binding.Path means the current item from the parent collection, but that won't as an ItemsSource value because it's not a collection:

<ItemsControl ItemsSource="{Binding /}">   <!-- This won't work  here -->

You also need to define your inner ItemsControl.ItemTemplate. Try something like this:

<ItemsControl ItemsSource="{Binding Children}">
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <StackPanel Orientation="Vertical" />
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    <ItemsControl.ItemTemplate>
        <DataTemplate> <!-- Bind to the whole data item (a collection) here -->
            <ItemsControl ItemsSource="{Binding}">
                <ItemsControl.ItemsPanel>
                    <ItemsPanelTemplate>
                        <StackPanel Orientation="Horizontal"/>
                    </ItemsPanelTemplate>
                </ItemsControl.ItemsPanel>
                <ItemsControl.ItemTemplate>
                    <DataTemplate> <!-- Display your BaseViewModel data items here -->
                        <YourXmlNamespacePrefix:YourControl DataContext="{Binding}" />
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ItemsControl>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>