Why LonglistSelector not display items though it display GroupHeaderItem? - xaml

Question

My LonglistSelector only displays GroupHeaderTemplate Data (ImageSource,Title) but ItemTemplate DataTemplate (SubItemTitle, Location) not displayed. How can i solve it?
public class Data
{
public string Title { get; set; }
public string ImageSource { get; set; }
public List<SubItem> SubItems { get; set; }
public Data()
{
SubItems = new List<SubItem>();
}
}
public class SubItem
{
public string SubItemTitle { get; set; }
public string Location { get; set; }
}
<phone:LongListSelector ItemsSource="{Binding DataCollection}" Grid.Row="0" IsGroupingEnabled="True">
<phone:LongListSelector.GroupHeaderTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Margin="10">
<Image Source="{Binding ImageSource}"/>
<TextBlock Text="{Binding Title}"/>
</StackPanel>
</DataTemplate>
</phone:LongListSelector.GroupHeaderTemplate>
<phone:LongListSelector.ItemTemplate>
<DataTemplate>
<StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding SubItemTitle}" Padding="5" FontSize="40"/>
<TextBlock Text="{Binding Location}" Padding="5" FontSize="40"/>
</StackPanel>
</StackPanel>
</DataTemplate>
</phone:LongListSelector.ItemTemplate>
</phone:LongListSelector>

Answer 1

You have to convert whatever the class you are using to group the items from inheriting. Try using the List than the IEnumerator.
This one discusses the same longlistselector issue.
Grouped LongListSelector: headers appear, items don't
Hope it helps!

Answer 2

This MSDN example helped me a lot when I had trouble understanding Grouping with LongListSelector
How to display data in a grouped list in LongListSelector for Windows Phone 8
It needs to be Grouped by a Key Value. Of all the of the examples I know of it's always something like this:
List<AlphaKeyGroup<your_data_type>> my_group_list; // or
ObservableCollection<AlphaKeyGroup<your_data_type>> my_group_list;
Not a List that has a property that is a SubList.
AlphaKeyGroup is just a List<T>/ObservableCollection<T> with an extra property for a Key
Think of it this way, in your code how does the LongListSelector know that your "Title" is the group key rather than the "ImageSource"?
If the code on the MSDN page is too complicated to understand, you can always take the easier route and use LINQ using the GroupBy.
Here a SO example: Group by in LINQ