Setup WPF Data Template With Class in Another Mudule

Question

Trying to bind a TreeView to a class that's in a module. I was fortunate to get this fabulous example from Peter Fleischer. In it he uses:

xmlns:local="clr-namespace:WpfApp1"

Then later:

<HierarchicalDataTemplate DataType="{x:Type local:Window63FntSetData}" ItemsSource="{Binding Fnts}">

In place of Peter's "Window63FntSetData" I need to reference a class that's in a module.

How do I do so in the XAML?

Thank you,
Ken

Answer 1

Hi Ken,
set reference in project to another dll and include additional namespace (from another dll) in XAML:

 xmlns:local="clr-namespace:WpfApp1"
 xmlns:externdll="clr-namespace:ExternalNamespace;assembly=ExternalAssembly"
...
 <HierarchicalDataTemplate DataType="{x:Type externdll:FntSetData}" ItemsSource="{Binding Fnts}"> 

Answer 2

Welcome to our Microsoft Q&A platform!

You could refer to the below step to add the class in XAML.

1. Create your model in MyVM.vb

      Public Class MyMoudle
   Public Property SetId As String
   Public Property SetName As String
   

   End Class
2. Add the MyMoudle data for Collection

       Public Class MyVM
   
   Private col As New ObservableCollection(Of MyMoudle)
   Private cvs As New CollectionViewSource
   
   Public ReadOnly Property MyDataItems As ICollectionView
       Get
           If cvs.Source Is Nothing Then GetData()
           Return cvs.View
       End Get
   End Property
   

   Private Sub GetData()
   'add data for col
   End Sub End Class
3. Bind the data in xaml using DataContext

   <Window.DataContext>
           <local:MyVM/>
       </Window.DataContext>
   

   4. You can bind the class in the Treeview Resource with set ItemsSource as your data collection [MyDataItems] <TreeView ItemsSource="{Binding MyDataItems}"….>
      <TreeView.Resources>
      <HierarchicalDataTemplate DataType="{x:Type local:MyMoudle}" … >
      ...
      </HierarchicalDataTemplate>
      </TreeView.Resources>
      </TreeView>

Thanks.

Answer 3

Thank so much for answering guys, but I think I should have been more specific.

The "module" I'm referring to is a .vb file in the project. Can what Peter suggested work that way?

And I think what AlexLi suggested is the REAL "right" way to do this (is it MVVM? showing my lack of knowledge here) but I should have said that I already have an established List(of) FntSetData and FntData and am currently building the StackPalnel and adding the items to the TreeViews with .Items.Add. I'm hoping that binding the data will speed up the build of the larger list view with 10,000+ itmes when their bound.

Currently looks like this:

I think the example that Peter supplied (linked in my original post) will get me there with some tweaking including making the "base" class (and figuring out how to add the icons to that mix) but the classes in the .vb file aren't "visible" to the XAML in the main window - if I'm even using the right terminology.

Thanks again,
Ken

Answer 4

Wow Peter! Can't thank you enough.

Will have a look this weekend.

All the best,
Ken

Answer 5

Got it working! My very large tree now gets built almost instantaneously! Thank you again!

The problem was my namespaces, or more appropriately lack there of. When I said earlier that the class was in a module I was hearkening back to VB6 and meaning just another file with in the project, a .VB file. But the problem was that it WAS in a ACTUAL module with the keyword "Module" and so the XAML couldn't "see" it. I created a namespace for it and added that name space to the XMAL to fix things up.

I found a few other things I needed this weekend with the exception of one. Before binding the data I was building the tree "manually" using a class I created inheriting form the TreeViewItem and added a couple of properties, like so:

I couldn't find a way in the XMAL to have the TreeView populate with my class rather than the usual TreeViewItem. Hoping it MIGHT help minimize the rewriting I have to do now that the data is bound.

Thank you, yet again, for all your help.

All the Best,
Ken