Setting the design time datacontext making the designer stop responding

I followed the Avalonia docs to set the datacontext but whenever I set it the designer suddenly stops responding to changes and hangs up until I remove the datacontext: I tried setting it using: d:DataContext="{x:Static dd:McalUiViewModelDesignData.ViewModel}" and
<Design.DataContext> <viewModels:ViewModel /> </Design.DataContext> and both doesn’t work

NOTES: I am using jetbrains rider IDE version “2022.1.1” and avaloniaRider version “1.0.0.2140933515”

[hhyyrylainen]

I just had a bug like this where my data context constructor was running into an exception. This unhandled exception doesn’t seem to be logged anywhere. After a lot of looking I realized what the problem was for me (I specifically removed the initialization of a component that is actually needed in design mode). I’m not 100% sure it was an exception, only just pretty sure based on the fact I was using a IServiceProvider that had a missing service and the preview started working once I added the service I realized was missing.

So it would be very nice if the rider avalonia output would show something more than:

System.IO.EndOfStreamException: Attempted to read past the end of the stream.
   at Avalonia.Remote.Protocol.BsonStreamTransportConnection.ReadExact(Byte[] buffer) in /_/src/Avalonia.Remote.Protocol/BsonStreamTransport.cs:line 59
   at Avalonia.Remote.Protocol.BsonStreamTransportConnection.Reader() in /_/src/Avalonia.Remote.Protocol/BsonStreamTransport.cs:line 71

when there are problems like this.

[WilbertOnGithub]

Just leaving this here in case someone else stumbles into this problem. I encountered the same issue as described by @hhyyrylainen where the logfile of the designer showed the following:

System.IO.EndOfStreamException: Attempted to read past the end of the stream.
   at Avalonia.Remote.Protocol.BsonStreamTransportConnection.ReadExact(Byte[] buffer) in /_/src/Avalonia.Remote.Protocol/BsonStreamTransport.cs:line 59
   at Avalonia.Remote.Protocol.BsonStreamTransportConnection.Reader() in /_/src/Avalonia.Remote.Protocol/BsonStreamTransport.cs:line 71

In my case, I’m using the MVVM toolkit and inject the viewmodel into the view using the following

public partial class ApartmentConfigurationView : UserControl
{
    public ApartmentConfigurationView()
    {
        InitializeComponent();
        DataContext = Ioc.Default.GetRequiredService<ApartmentConfigurationViewModel>();
    }

    private void InitializeComponent()
    {
        AvaloniaXamlLoader.Load(this);
    }
}

Then I added a design time reference to the view to preview my data:

   <Design.DataContext>
        <viewModels:ApartmentConfigurationViewModel/>
    </Design.DataContext>

Turns out that I forgot to register the viewmodel for usage with dependency injection. After registering it, the preview started working.

And I agree that the previewer should preferably give more helpful error message on what is actually happening 😃