Adding to C# API Demo -- DataTemplateSelector not working

23 Apr 2015, 17:02

Knowing now that the BuildTool does not yet allow use of C# classes in the xaml, I have switched to setting the ItemControl's ItemSource and ItemTemplate in my C# code and that is working.
Unfortunately, when I set ItemTemplateSelector instead, it is NOT working.

In my xaml, I'm defining a DataTemplate resource and an ItemsControl that will make use of it.

<UserControl.Resources>
        <DataTemplate x:Key="TextDataTemplate_key">
            <TextBlock  Text="{Binding StatusItemText}" 	/>
        </DataTemplate>
</UserControl.Resources>

<Grid>
	<ItemsControl x:Name="State_StatusBarArea" >
		<ItemsControl.ItemsPanel>
			  <ItemsPanelTemplate>
				<StackPanel Orientation="Horizontal"/>
			  </ItemsPanelTemplate>
		</ItemsControl.ItemsPanel>
	</ItemsControl>
</Grid>

In my C# code, I'm successfully setting the ItemSource and the ItemTemplate.

//Load xaml and find the ItemsControl
UserControl userControl = Noesis.GUI.Load("StatusBarAndNotificationsControl.xaml") as UserControl;
object itemsObject = userControl.FindName("State_StatusBarArea");
ItemsControl control = itemsObject as ItemsControl;

//set ItemSource to data model's ObservableCollection property
StateStatusModel = new StatusBarAreaModel();
StateStatusModel.SetItem(0, "First", "Fred", null);
control.ItemsSource = StateStatusModel.StatusBarItemList;

//Find the DataTemplate resource and use it to set the ItemsControl ItemTemplate
DataTemplate textDataTemplate = userControl.FindResource("TextDataTemplate_key") as DataTemplate;
control.ItemTemplate = textDataTemplate;

This works fine.

But if I define a DataTemplateSelector class

    public class StatusItemTemplateSelector : DataTemplateSelector
    {
        public override DataTemplate SelectTemplate(object item, DependencyObject container)
        {
            return TextDataTemplate;
        }

        public DataTemplate TextDataTemplate { get; set; }
    }

and assign this template selector in my C# code

StatusItemTemplateSelector selector = new StatusItemTemplateSelector();
selector.TextDataTemplate = textDataTemplate;

control.ItemTemplateSelector = selector;

This does NOT work.

What am I doing wrong?

23 Apr 2015, 20:42

There is nothing wrong in your code, is just that DataTemplateSelector classes implemented in C# are not working yet. Native code is not calling the virtual function of the managed class

This feature is only working in the Native API right now. If you want, you can create a ticket in our bugtracker to follow the status of its development. We will fix it as soon as possible.

31 Jul 2019, 22:02

Has this been implemented yet? I just tried it and it doesn't seem to be working for me. I'll add a feature request in the bugtracker if it's not...

01 Aug 2019, 17:41

Hello,

It is already implemented in Noesis C# API. I just tried the following scenario that works fine:

namespace MyNamespace
{
    public class TestDataTemplateSelector : DataTemplateSelector
    {
        public DataTemplate Even { get; set; }
        public DataTemplate Odd { get; set; }

        public override DataTemplate SelectTemplate(object item, DependencyObject container)
        {
            int n = int.Parse(item.ToString());
            return (n % 2) == 0 ? Even : Odd;
        }
    }
}

<Grid
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:local="clr-namespace:MyNamespace">

    <Grid.Resources>
        <DataTemplate x:Key="EvenTemplate">
            <TextBlock Text="{Binding}" Foreground="Red"/>
        </DataTemplate>
        <DataTemplate x:Key="OddTemplate">
            <TextBlock Text="{Binding}" Foreground="Blue"/>
        </DataTemplate>
        <local:TestDataTemplateSelector x:Key="TemplateSelector" Even="{StaticResource EvenTemplate}" Odd="{StaticResource OddTemplate}"/>
    </Grid.Resources>
    
    <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
        <ContentControl Content="1235" ContentTemplateSelector="{StaticResource TemplateSelector}"/>
        <ContentControl Content="26442" ContentTemplateSelector="{StaticResource TemplateSelector}"/>
   </StackPanel>
    
</Grid>

What is not working in your case?

01 Aug 2019, 18:40

*sigh*... I uncommented my DataTemplateSelector and now it's working. I'm not sure what I was doing wrong... checked it multiple times. Probably had the resource key misspelled or something.

02 Aug 2019, 12:39

Great to know it is working for you also. thanks for the update.

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