Reflection not support custom xaml control

[SongOfYouth]

Current behavior

I have a custom class named BasePage (empty class) which inherited the Page class, and another class named MainPage inherited the BasePage, when i create a instance of MainPage by reflection,i got a error: Microsoft.UI.Xaml.Markup.XamlParseException:“XAML parsing failed.”, but if i refer the project which the MainPage in,and reflect it or create it by new,it works.

Works on UWP/WinUI

None

Environment

Uno.WinUI / Uno.WinUI.WebAssembly / Uno.WinUI.Skia

Affected platforms

Windows

IDE

Visual Studio 2022

[SongOfYouth]

trailed some times, I find the reason. The compiler will generate a XamlTypeInfo.g.cs file when building, which the XamlTypeInfoProvider of other project will be builded in when reference other project with ProjectReference, and this section is missing when reflect a assembly directly. My solution code is :
in App.cs:

var appProviderProperty = this.GetType().GetProperty("_AppProvider", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
var appProvider = appProviderProperty!.GetValue(this)!;
var appProviderProviderProperty = appProvider.GetType().GetProperty("Provider", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
var appProviderProvider = appProviderProviderProperty!.GetValue(appProvider);
var othersProperty = appProviderProvider!.GetType().GetProperty("OtherProviders", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
var otherProviders = othersProperty!.GetValue(appProviderProvider) as List<Microsoft.UI.Xaml.Markup.IXamlMetadataProvider>;
var originType = Assembly.Load("MyAssembly").GetType("MyAssembly.MyAssembly_XamlTypeInfo.XamlMetaDataProvider");
var provider = Activator.CreateInstance(originType!) as Microsoft.UI.Xaml.Markup.IXamlMetadataProvider;
otherProviders!.Add(provider!);

Is it possible to provide a frendly way to do it in future?

[jeromelaban]

I'm not sure to understand what you're trying to do, and the error you had originally. If you can provide more details about the scenario you're trying to get working, it will help.

Note that if the issue happens when running the Windows head, this will be a WinUI issue, not an Uno issue.

[SongOfYouth]

I think it's possibly a WinUI issue. as the reply saying, I want to load a control(eg. Page inherited from a custom page class) from assembly file at runtime, When I reflect it directly and create a instance, I get the error above, and when i reference the project of this assembly by ProjectReference and reflect it, it works! I have found that, in the XamlTypeInfo.g.cs file, the XamlTypeInfoProvider of the assembly I reflected will be add to the OtherProviders collection when reference it by ProjectReference , I think that's the difference.