Is it possible to use dialogs with the Elmish hooks?

[marklam]

I'm using the Elmish hooks in the component model, but I can't get dialog.ShowAsync to work from the update method.

The non-hook Elmish version has Cmd.OfAsync, which is used in the MusicPlayer sample, but the hook version only has Cmd.ofMsg. to get the payload for the message, I have to await the ShowAsync in the update function. Awaiting the ShowAsync seems to hang even if I use the Dispatcher.UIThread (this is on Windows BTW).

Any help would be greatly appreciated!

My update function is handler below with windowParams partially applied to supply the parent window

        type WindowParams = { Window : Window }
        type Msg = | PickProjectFile | SetProjectFile of string

        let handler windowParams msg model =
            match msg with
            | PickProjectFile ->
                let saveFileTask =
                    Dispatcher.UIThread.InvokeAsync<string>(
                        System.Func<System.Threading.Tasks.Task<string>>(fun () ->
                            let dialog = SaveFileDialog()
                            dialog.ShowAsync windowParams.Window
                        ))

                model, saveFileTask.Result |> SetProjectFile |> Cmd.ofMsg

Thanks.

[JordanMarr]

Thanks for posting your issue. The useElmish hook is still a very barebones implementation.
However, I am definitely interested in adding proper async support, so I'll take a pass at it.

[marklam]

Thanks, that would be great!

[JordanMarr]

Also, you may need to add [<System.STAThread>] attribute to your main fn.

[marklam]

Unfortunately that doesn't seem to fix it.

[marklam]

I've added some sample code at https://github.com/marklam/FuncUIFileDialog

It's a standalone solution (using paket - so dotnet tool restore before dotnet build), but I've also included an fsproj file which could be used to drop the project folder into the src folder of the Avalonia.FuncUI repo for easier testing.

[marklam]

Please Ignore this comment, it's fixed (explanation in the replies)

As a side note, the AppBuilder needs a call to .With(Win32PlatformOptions(UseWgl = true)) otherwise the app throws the exception eglCreatePbufferFromClientBuffer failed with error EGL_BAD_ATTRIBUTE (0x3004) at

	Avalonia.OpenGL.dll!Avalonia.OpenGL.Egl.EglPlatformOpenGlInterface.CreatePBufferFromClientBuffer(int bufferType, System.IntPtr handle, int[] attribs) Line 67	C#
 	Avalonia.OpenGL.dll!Avalonia.OpenGL.Angle.AngleWin32EglDisplay.WrapDirect3D11Texture(Avalonia.OpenGL.Egl.EglPlatformOpenGlInterface egl, System.IntPtr handle, int offsetX, int offsetY, int width, int height) Line 92	C#
 	Avalonia.Win32.dll!Avalonia.Win32.WinRT.Composition.WinUiCompositedWindowSurface.CompositionRenderTarget.BeginDraw() Line 75	C#
 	Avalonia.Skia.dll!Avalonia.Skia.GlRenderTarget.BeginRenderingSession() Line 63	C#
 	Avalonia.Skia.dll!Avalonia.Skia.SkiaGpuRenderTarget.CreateDrawingContext(Avalonia.Rendering.IVisualBrushRenderer visualBrushRenderer) Line 27	C#
 	Avalonia.Visuals.dll!Avalonia.Rendering.DeferredRenderer.EnsureDrawingContext(ref Avalonia.Platform.IDrawingContextImpl context) Line 617	C#
 	Avalonia.Visuals.dll!Avalonia.Rendering.DeferredRenderer.UpdateRenderLayersAndConsumeSceneIfNeeded(ref Avalonia.Platform.IDrawingContextImpl context, bool recursiveCall) Line 376	C#
 	Avalonia.Visuals.dll!Avalonia.Rendering.DeferredRenderer.Render(bool forceComposite) Line 323	C#
 	Avalonia.Visuals.dll!Avalonia.Rendering.DeferredRenderer.Avalonia.Rendering.IRenderLoopTask.Render() Line 276	C#
 	Avalonia.Visuals.dll!Avalonia.Rendering.RenderLoop.TimerTick(System.TimeSpan time) Line 145	C#
 	Avalonia.Win32.dll!Avalonia.Win32.WinRT.Composition.WinUICompositorConnection.RunLoopHandler.Invoke(Avalonia.Win32.WinRT.IAsyncAction asyncInfo, Avalonia.Win32.WinRT.AsyncStatus asyncStatus) Line 107	C#
 	Avalonia.Win32.dll!Avalonia.Win32.WinRT.Impl.__MicroComIAsyncActionCompletedHandlerVTable.Invoke(void* this, void* asyncInfo, Avalonia.Win32.WinRT.AsyncStatus asyncStatus) Line 2879	C#
 	[Native to Managed Transition]	
 	[Managed to Native Transition]	
 	Avalonia.Win32.dll!Avalonia.Win32.WinRT.Composition.WinUICompositorConnection.RunLoop() Line 131	C#
 	Avalonia.Win32.dll!Avalonia.Win32.WinRT.Composition.WinUICompositorConnection.TryCreateAndRegisterCore.AnonymousMethod__0() Line 81	C#
 	System.Private.CoreLib.dll!System.Threading.Thread.StartCallback() Line 106	C#

The strange thing is that the call isn't needed if the demo project is built & run within the Avalonia.FuncUI tree, with project references rather than nuget package references.

Is this a known/expected thing, or should I create a separate bug/issue for it?

[Numpsy]

I can't comment on the elmish part, but for differences between using the nugets and building in the tree - are you using the same versions of things in both cases? (the sample project you linked looks to be using Avalonia 10, and the latest code in the tree is Avalonia 11, and there are quite a lot of changes over there)

[marklam]

Long story short, I found that the OpenGL problem happened because I wasn't asking paket to resolve the dependencies in the right way.

Short story long,

• I made a branch from the 0.5.3 release at https://github.com/marklam/Avalonia.FuncUI/tree/needs-use-wgl
• I created a test app using ProjectReference and one using PackageReference and they both worked fine.
• I then tried using paket instead of PackageRererence, and it didn't work.
• I compared the *.deps.json files and found that dependencies-of-dependencies were mismatched versions.
• I removed the paket reference to Avalonia.Desktop and set strategy:min on the FuncUI references.
• Then it worked as expected.

I'll update the elmish sample I addd to use PackageReference, to avoid this trip-hazard.

[JordanMarr]

The next prerelease will have a completely reworked useElmish hook that will be fully based off of Elmish 4, so it will have all the latest async handlers.

#251

[marklam]

Can confirm this works now.

Many thanks!