Listbox ItemTemplate Selector does not pick a template

Question

I am trying to use an ItemTemplateSelector on a listbox within a grid that I am creating on a different file to later be called by the MainWindow.

Here is my DataTe

Answer 1

@Rachel is right. Your DataTemplateSelector only gets invoked once at load pretty much and not for INPC changes.

What you can do for what you require is use a ListBoxItemStyle with DataTrigger switching the Template used

something like:

<ControlTemplate x:Key="greenItemTemplate">
  <Border BorderBrush="Green"
          BorderThickness="3">
    <StackPanel HorizontalAlignment="Stretch">
      <TextBlock Text="{Binding Path=GroupName}" />
      <TextBlock Text="{Binding Path=myType}" />
    </StackPanel>
  </Border>
</ControlTemplate>
<ControlTemplate x:Key="redItemTemplate">
  <Border BorderBrush="Red"
          BorderThickness="3">
    <StackPanel HorizontalAlignment="Stretch">
      <TextBlock Text="{Binding Path=GroupName}" />
      <TextBlock Text="{Binding Path=myType}" />
    </StackPanel>
  </Border>
</ControlTemplate>
<ControlTemplate x:Key="yellowItemTemplate">
  <Border BorderBrush="Yellow"
          BorderThickness="3">
    <StackPanel HorizontalAlignment="Stretch">
      <TextBlock Text="{Binding Path=GroupName}" />
      <TextBlock Text="{Binding Path=myType}" />
    </StackPanel>
  </Border>
</ControlTemplate>
<Style x:Key="MyListBoxItemStyle"
        TargetType="{x:Type ListBoxItem}">
  <Setter Property="Template"
          Value="{DynamicResource greenItemTemplate}" />
  <Style.Triggers>
    <DataTrigger Binding="{Binding myType}"
                  Value="c">
      <Setter Property="Template"
              Value="{DynamicResource redItemTemplate}" />
    </DataTrigger>
    <DataTrigger Binding="{Binding myType}"
                  Value="b">
      <Setter Property="Template"
              Value="{DynamicResource yellowItemTemplate}" />
    </DataTrigger>
  </Style.Triggers>
</Style>

and usage:

<ListBox ItemContainerStyle="{StaticResource MyListBoxItemStyle}"
         ItemsSource="{Binding myCollectionOfMyClassObjects}" 
         Name="listBox1"
         HorizontalContentAlignment="Stretch" />