worldbeater
commented
5 years ago A temporary solution is to extract the DataTemplate into a separate UserControl, and then embed it into the DataTemplate. Generally, this approach is a lot more MVVMish than using event handlers, so a rule of thumb is to always create user controls and view models for them when working with DataTemplates. If you need to bind to the DataContext (view model) of a parent control, then a wise decision would be to pass a reference to the parent view model down to children view models.
For example, on the parent control side it could look like as follows:
<ListBox SelectionMode="Toggle" Items="{Binding Files}">
<ListBox.ItemTemplate>
<DataTemplate DataType="interfaces:IFileViewModel">
<views:FileView DataContext="{Binding}" />
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>And on the child control side it would be:
<UserControl xmlns="https://github.com/avaloniaui"
x:Class="Camelotia.Presentation.Avalonia.Views.FileView"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
PointerReleased="OnPointerReleased">
<TextBlock Text="{Binding Name}" />
</UserControl>With the following code-behind:
public sealed class FileView : ReactiveUserControl<IFileViewModel>
{
public FileView()
{
AvaloniaXamlLoader.Load(this);
this.WhenActivated(disposables =>
{
Observable // Using Observables and ReactiveUI is possible as well
.FromEventPattern<PointerReleasedEventHandler, PointerReleasedEventArgs>(
handler => PointerReleased += handler,
handler => PointerReleased -= handler)
.Subscribe(args => Console.WriteLine("It also works with observables!"))
.DisposeWith(disposables);
});
}
// This works fine and throws no exceptions!
public void OnPointerReleased(object sender, PointerReleasedEventArgs args)
{
Console.WriteLine("It works with events!")
}
}
grokys
kekekeks
balthild
While struggling to prevent the
ListBoxfrom handling right mouse button clicks which are intended to be used for showingContextMenus and not selecting anything in theListBox, I discovered that event handlers won't work when referencing the handler method from a control declared inside aDataTemplate.The following setup doesn't work
and
will result into
PotableXamlexception:the new XamlIl compiler throws the following at runtime, much more descriptive btw:
The following setup works
and
will result into a working application triggering the
OnPointerReleasedevent handler.Repro
The repro can be found here.