无法在 2 个程序集（UWP、Splat）之间注册 View 和 ViewModel

Question

使用最新的 RxUI v8 预览版和 Splat 2.0，在引用 .Net Standard 2.0 库的 UWP 项目中，我无法注册我的视图和视图模型，除非它们位于同一程序集中。

我有：

Locator.CurrentMutable.RegisterLazySingleton(() => new HomeView(), typeof(IViewFor<HomeViewModel>));

但是Splat报错：

DefaultViewLocator: Failed to find type named 'RxUI.UWP.Core.Views.HomeView, RxUI.UWP.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.
DefaultViewLocator: Failed to resolve service for type 'ReactiveUI.IViewFor`1[[RxUI.UWP.Core.ViewModels.HomeViewModel, RxUI.UWP.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]'.
DefaultViewLocator: Failed to find type named 'ReactiveUI.IRoutableView, ReactiveUI, Version=8.0.0.0, Culture=neutral, PublicKeyToken=null'.
DefaultViewLocator: Failed to resolve service for type 'ReactiveUI.IViewFor`1[[ReactiveUI.IRoutableViewModel, ReactiveUI, Version=8.0.0.0, Culture=neutral, PublicKeyToken=null]]'.
DefaultViewLocator: Failed to resolve view for view model type 'ReactiveUI.IRoutableViewModel'.
DefaultViewLocator: Failed to find type named 'RxUI.UWP.Core.Views.HomeView, RxUI.UWP.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.

所以它在 "Core" 程序集中寻找 HomeView，但它驻留在 UWP 项目中。这是结构...

Answer 1

我在与您类似的环境中遇到了同样的问题。 The issue resided in the DefaultViewLocator，因为视图类型被重命名并错误地解析为视图模型的程序集和命名空间。查看第 133-134 行查看视图类型名称是如何确定的：

var viewModelTypeName = viewModelType.AssemblyQualifiedName;
var proposedViewTypeName = this.ViewModelToViewFunc(viewModelTypeName);

注意：ViewModelToViewFunc 只是一个 String.Replace 将 "ViewModel" 替换为 "View"（参见构造函数）。

为了解决这个问题，我的解决方法是创建我自己的 IViewLocator 实现，例如：

public class MyViewLocator : IViewLocator {
   public MyViewModelLocator(Assembly viewAssembly, string viewNameSpace)
...
   private IViewFor AttemptViewResolutionFor(Type viewModelType, string contract)
    {
        // proposed view type is now based on provided namespace + classname as modified by ViewModelToViewFunc
        if (viewModelType == null) return null;
        var viewModelTypeName = viewModelType.Name;
        var proposedViewTypeName = _viewNamespace + "." +  this.ViewModelToViewFunc(viewModelTypeName);
...

   private IViewFor AttemptViewResolution(string viewTypeName, string contract)
    {
        try
        {
            // resolve view type in the assembly of the view, and not assembly of the viewmodel
            var viewType = _viewAssembly.GetType(viewTypeName); // instead of Reflection.ReallyFindType(viewTypeName, throwOnFailure: false);
...
}

最后，您的自定义 viewlocator 实现必须向 splat 注册，以便它覆盖 DefaultViewLocator 实现：

Locator.CurrentMutable.RegisterConstant<IViewLocator>(new MyViewLocator(typeof(SplashView).Namespace, typeof(SplashView).Assembly));

无法在 2 个程序集（UWP、Splat）之间注册 View 和 ViewModel

Can't register a View and ViewModel between 2 assemblies (UWP, Splat)

c#

reactiveui

splat

.net-standard-2.0