升级到 Prism 8 导致导航错误

Question

环境

• Xamarin 表单：5.0.0.1709-pre4（但也会因 4.8.0.1687 而失败）
• VS2019 16.8.3
• X 代码：12.2

Prism NuGet

• Prism.DryIoc.Extensions 8.0.48
• Prism.Forms 8.0.0.1909
• Prism.PluginPopups 8.0.31-beta
• Shiny.Prism 8.0.48

INavigationResult 的内部异常：DryIoc.ContainerException -> InvalidOperationException

    code: Error.UnableToResolveFromRegisteredServices;
    message: Unable to resolve Resolution root IRMobile.PageModels.LandingPageModel with passed arguments 
    [Constant(Prism.Navigation.ErrorReportingNavigationService, 
    typeof(Prism.Navigation.ErrorReportingNavigationService))]
      from container with scope {Name=null}
     with Rules with {TrackingDisposableTransients, UseDynamicRegistrationsAsFallbackOnly, 
    FuncAndLazyWithoutRegistration, SelectLastRegisteredFactory} and without 
    {ThrowOnRegisteringDisposableTransient, UseFastExpressionCompilerIfPlatformSupported}
     with FactorySelector=SelectLastRegisteredFactory
     with Made={FactoryMethod=ConstructorWithResolvableArguments}
      with normal and dynamic registrations:
      (DefaultDynamicKey(0), {FactoryID=317, ImplType=IRMobile.PageModels.LandingPageModel, 
    Reuse=TransientReuse, HasCondition})

来自 InnerException 的堆栈跟踪：

  at DryIoc.Container.TryThrowUnableToResolve (DryIoc.Request request) [0x00058] in /_/src/DryIoc/Container.cs:1077 
  at DryIoc.Container.DryIoc.IContainer.ResolveFactory (DryIoc.Request request) [0x00072] in /_/src/DryIoc/Container.cs:1059 
  at DryIoc.Container.ResolveAndCacheKeyed (System.Int32 serviceTypeHash, System.Type serviceType, System.Object serviceKey, DryIoc.IfUnresolved ifUnresolved, System.Object scopeName, System.Type requiredServiceType, DryIoc.Request preResolveParent, System.Object[] args) [0x000c5] in /_/src/DryIoc/Container.cs:471 
  at DryIoc.Container.DryIoc.IResolver.Resolve (System.Type serviceType, System.Object serviceKey, DryIoc.IfUnresolved ifUnresolved, System.Type requiredServiceType, DryIoc.Request preResolveParent, System.Object[] args) [0x00042] in /_/src/DryIoc/Container.cs:430 
  at DryIoc.Resolver.Resolve (DryIoc.IResolver resolver, System.Type serviceType, System.Object[] args, DryIoc.IfUnresolved ifUnresolved, System.Type requiredServiceType, System.Object serviceKey) [0x00000] in /_/src/DryIoc/Container.cs:7809 
  at Prism.DryIoc.DryIocContainerExtension.Resolve (System.Type type, System.ValueTuple`2[System.Type,System.Object][] parameters) [0x0001c] in /_/external/Prism/src/Containers/Prism.DryIoc.Shared/DryIocContainerExtension.cs:294 

App.xaml.cs

    protected override void RegisterTypes(IContainerRegistry containerRegistry)
        {
            // for RgPopups
            containerRegistry.RegisterPopupNavigationService();
            containerRegistry.RegisterPopupDialogService();

            // Essentials
            containerRegistry.Register<ISecureStorage, SecureStorageImplementation>();
            containerRegistry.RegisterSingleton<IAppInfo, AppInfoImplementation>();

            // page stuff
            containerRegistry.RegisterForNavigation<NavigationPage>();
            containerRegistry.RegisterForNavigation<IconNavigationPage>();
            containerRegistry.RegisterSingleton<IPageBehaviorFactory, CustomPageBehaviorFactory>();

            ...
            // Page and model registrations
containerRegistry.RegisterForNavigation<LoginPage, LoginPageModel>();
            containerRegistry.RegisterForNavigation<LandingPage, LandingPageModel>();

        }

我在尝试从 LoginPage 导航到根主/详细信息页面时遇到此异常

await NavigationService.NavigateAsync("/MainPage/NavigationPage/LandingPage")

LandingPage 的构造函数是

public LandingPageModel(INavigationService navigationService, IMapper mapper, IDialogs dialogs, IPushManager pushManager) : base(navigationService, mapper)

我对 Prism 还很陌生，所以我确定我缺少一些东西，一个注册或者一个 NuGet 包，但我不确定它会是什么。当我遇到同样的错误时，我注释掉了弹出窗口的注册，但指的是Prism.Plugin.Popups.PopupPageNavigationService

一如既往，感谢您的帮助！

Answer 1

您似乎正在尝试导航到名为 LandingPage 的页面，但您尚未告诉容器 LandingPage 是什么。

每次您想要创建一个新视图并导航到它时，您都需要在您的 App.Xaml.cs 文件中为 Navigation 注册它；

containerRegistry.RegisterForNavigation<LandingPage, LandingPageViewModel>();

这一行在容器内注册了视图及其对应的 ViewModel。一旦容器知道视图，NavigationService 就可以使用视图的文字名称 LandingPage 解析您希望导航到的视图。

现在你可以打电话了

await NavigationService.NavigateAsync("LandingPage");
//or
await NavigationService.NavigateAsync("/MainPage/NavigationPage/LandingPage")

注意

Prism 导航内置了一些巧妙的技巧。它是基于 Uri 的，因此每次导航到另一个视图时，在 NavigateAsync 方法中传递视图的名称会将视图堆叠在其他视图之上。这意味着，如果你从 URI NavigationPage/PageA 开始，然后你说 NavigateAsync("PageB")，你将在 NavigationPage/PageA/PageB 结束。

此外，在 NavigateAsync 参数的开头包含 / 字符会完全重置堆栈。因此，如果您从 NavigationPage/PageA/PageB 导航到 /PageC，这会将堆栈重置为 PageC