Tree View won't load child items

3 posts, 1 answers
  1. jason
    jason avatar
    28 posts
    Member since:
    Oct 2010

    Posted 26 Jun 2011 Link to this post

    I am trying to write the treeview control using LoadOnDemand and HierarchialDataTemplates.  The parent nodes load fine but then when I click on one the loading circle runs and nothing else happens.  I have stepped through the code and Folders (an ObservableCollection<FolderNode>) does have data so not sure what is wrong.  here is my xaml:

    <UserControl.Resources >
            <DataTemplate x:Key="FolderItemTemplate">
                <TextBlock Text="{Binding FolderName}"/>
            <telerik:HierarchicalDataTemplate x:Key="WorkspaceTemplate" ItemsSource="{Binding Folders}" ItemTemplate="{StaticResource FolderItemTemplate}">
                    <TextBlock Text="{Binding Name}"/>
        <Grid x:Name="LayoutRoot" Background="White">
            <nav:RadTreeView ItemTemplate="{StaticResource WorkspaceTemplate}" IsExpandOnSingleClickEnabled="True" ItemsSource="{Binding Workspaces}" IsLoadOnDemandEnabled="True" LoadOnDemand="RadTreeView_LoadOnDemand">
  2. jason
    jason avatar
    28 posts
    Member since:
    Oct 2010

    Posted 27 Jun 2011 Link to this post

    I have gotten beyond my original problem now as I did not realize that 'Folders' had to be an IEnumerable inside Workspaces.  My problem now is that I have this hierarchy:  Workspaces --> Folders.  Folders will not have any child items in the tree because when you click on a folder it will load the document list into a grid.  My problem is that after I expand a workspace then folders can also be expanded.  How can I make it so Folders is the bottom level?  I thought my hierarchialdatatemplate referencing just a DataTemplate would take care of that but apparently not.
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  4. Answer
    Petar Mladenov
    Petar Mladenov avatar
    2882 posts

    Posted 29 Jun 2011 Link to this post

    Hello jason,

    There are two basic approaches to handle this. The first is "code-behind" solution and it uses the ItemPrepared event of the RadTreeView - it fires every time a container ( RadTreeViewItem is prepared). In your case you will have to do something like;
    if( e.PreparedItem.Item is Folder)
         e.Prepareditem.IsLoadOnDemandEnabled = false;
    The second approach should be used if you use ViewModels to wrap your business objects (or objects from a DB). You can expose a boolean property in your FolderViewModel and bind it to the IsLoadOnDemandEnabled property of the RadTreeViewItem via ContainerBindings.
    Please let us know if this helped you.

    Petar Mladenov
    the Telerik team
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