WPF Expander Hierarchical data Template of 2 levels - wpf

Question

I have a repeating data structure like this
public class Chapter
{
public string id { get; set; }
public string name { get; set; }
public List<BPage> pages { get; set; }
public List<SubChapter> chapters { get; set; }
}
public class SubChapter
{
public string name { get; set; }
public string id { get; set; }
public List<BPage> pages { get; set; }
public string ParentPageId { get; set; }
public List<SubChapter> chapters { get; set; }
}
public class BPage
{
public string name { get; set; }
public string label { get; set; }
}
Here is the xaml i am using , But this xaml is giving only one level of data back to me . Second level is missing completely
ie if Chapter 1 contains 2 subchapters and pages , then those info is missing
Chapter 1
page 1
page 2
Chapter 1.1
page 1a
page 1b
Chapter 1.2
page 2a
page 2b
And xaml is
<ListBox ItemsSource="{Binding}" Name="TOCView" ItemContainerStyle="{StaticResource ListBoxItemStyle}">
<ListBox.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding chapters}">
<Expander>
<Expander.Header>
<BulletDecorator>
<Label Style="{StaticResource ResourceKey=ChapterHeadStyle}" Content="{Binding name}"></Label>
</BulletDecorator>
</Expander.Header>
<ItemsControl Margin="25,0,0,0" ItemsSource="{Binding pages}" >
<ItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel>
<Button Tag="{Binding}" Click="btnNavigateToPage_Click" Style="{StaticResource ResourceKey=BookPageStyle}" Content="{Binding Path=label}" >
</Button>
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Expander>
</HierarchicalDataTemplate>
</ListBox.ItemTemplate>
</ListBox>

Answer 1

Your problem is caused because you have only provided one HierarchicalDataTemplate, but you want to define two hierarchical levels. Therefore, you need to provide another HierarchicalDataTemplate for your second level. Please note that you do not have to define them in the ListBox.ItemTemplate property, instead defining them both in a Resources section:
<HierarchicalDataTemplate DataType="{x:Type YourPrefix:Chapter}"
ItemsSource="{Binding CollectionPropertyInSubChapterClass}">
...
</HierarchicalDataTemplate>
<HierarchicalDataTemplate DataType="{x:Type YourPrefix:SubChapter}">
ItemsSource="{Binding CollectionPropertyInBPageClass}">
...
</HierarchicalDataTemplate>
As long as you don't specify the x:Key directive for either of them, they will be implicitly applied, so you won't have to provide any value for the ListBox.ItemTemplate property.