HierarchicalDataTemplate and DataType: XAML parser error

Question

Hi,

I'm trying to use in my MVVM SL5 application a TreeView with a HierarchicalDataTemplate with a couple of implicit data templates, one for each of my viewmodels. The code compiles fine, but at runtime I get a XamlParserException telling that "Items added to a dictionary must have a key". Of course I can add the key, but this defeats the whole purpose of implicit type-based templating, and how could I work around this in the context of a hierarchical template to be used as source of a TreeView? Could anyone help? Here is a dummy code fragment similar to my real-world XAML:

<sdk:TreeView ItemsSource="{Binding Path=Segments,Mode=OneWay}">
  <sdk:TreeView.ItemContainerStyle>
    <Style TargetType="sdk:TreeViewItem">
      <Setter Property="IsExpanded" Value="{Binding Path=IsExpanded,Mode=TwoWay}"/>
      <Setter Property="IsSelected" Value="{Binding Path=IsSelected,Mode=TwoWay}"/>
      <Setter Property="FontWeight" Value="Normal"/>
    </Style>
  </sdk:TreeView.ItemContainerStyle>

  <sdk:TreeView.Resources>
    <sdk:HierarchicalDataTemplate DataType="dummy:Customer"
                    ItemsSource="{Binding Path=Products,Mode=OneWay}">
      ...template...
    </sdk:HierarchicalDataTemplate>

    <DataTemplate DataType="dummy:Product">
     ...template...
    </DataTemplate>
  </sdk:TreeView.Resources>
</sdk:TreeView>

 

Answer 1

Hi

Refer the Thred and a sample is there about implicit DataTemplates

http://blogs.msdn.com/b/cdndevs/archive/2011/06/13/silverlight-5-takes-datatemplate-to-the-next-level-with-implicit-data-templates.aspx

Answer 2

Thank you, I checked the sample but it does not seem to be different from my code, apart from the fact that the templates are declared in a separate resources dictionary. I tried moving them upper into the resources of the usercontrol containing the treeview, but nothing changes. Yet, the syntax should be simple: DataType="mynamespace:MyType". Any suggestion?

Answer 3

Here is a complete repro solution, showing exactly the error I'm talking about. Could anyone give a suggestion?

http://www.mediafire.com/?s653gsbj83i6rjd

Answer 4

you are using 

HierarchicalDataTemplate

Change

HierarchicalDataTemplate to DataTemplate.. your solution works..

HierarchicalDataTemplate is not supported for implicit conversion..

Answer 5

Thank you, I did not know about this limitation!