发布：2022/1/18 17:14:10作者：管理员 来源：本站 浏览次数：2171

.NET Core 的版本是 3.1

遇到的问题是 Action 中 return View() 的时候报错

An unhandled exception occurred while processing the request.

InvalidOperationException: No service for type 'Microsoft.AspNetCore.Mvc.ViewFeatures.ITempDataDictionaryFactory' has been registered.

Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)

错误内容的字面意思是 ITempDataDictionaryFactory 这玩意没有注册。

解决方案一：

修改 Startup.cs 中的 ConfigureServices方法

       public void ConfigureServices(IServiceCollection services)

       {

           services.AddMvc();

       }

解决方案二：

修改 Startup.cs 中的 ConfigureServices方法

       public void ConfigureServices(IServiceCollection services)

       {

           services.AddControllersWithViews();

       }

查看AspNetCore.Mvc 的源码

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       public static IMvcBuilder AddMvc(this IServiceCollection services)

       {

           if (services == null)

           {

               throw new ArgumentNullException(nameof(services));

           }

           services.AddControllersWithViews();

           return services.AddRazorPages();

       }

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AddMvc 方法中包含了 AddControllersWithViews

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       public static IMvcBuilder AddControllersWithViews(this IServiceCollection services)

       {

           if (services == null)

           {

               throw new ArgumentNullException(nameof(services));

           }

           var builder = AddControllersWithViewsCore(services);

           return new MvcBuilder(builder.Services, builder.PartManager);

       }

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跳转到 AddControllersWithViewsCore

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       private static IMvcCoreBuilder AddControllersWithViewsCore(IServiceCollection services)

       {

           var builder = AddControllersCore(services)

               .AddViews()

               .AddRazorViewEngine()

               .AddCacheTagHelper();

           AddTagHelpersFrameworkParts(builder.PartManager);

           return builder;

       }

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跳转到 AddViews

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       public static IMvcCoreBuilder AddViews(this IMvcCoreBuilder builder)

       {

           if (builder == null)

           {

               throw new ArgumentNullException(nameof(builder));

           }

           builder.AddDataAnnotations();

           AddViewComponentApplicationPartsProviders(builder.PartManager);

           AddViewServices(builder.Services);

           return builder;

       }

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跳转到 AddViewServices

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       internal static void AddViewServices(IServiceCollection services)

       {

           services.AddDataProtection();

           services.AddAntiforgery();

           services.AddWebEncoders();

           services.TryAddEnumerable(

               ServiceDescriptor.Transient<IConfigureOptions<MvcViewOptions>, MvcViewOptionsSetup>());

           services.TryAddEnumerable(

               ServiceDescriptor.Transient<IConfigureOptions<MvcOptions>, TempDataMvcOptionsSetup>());

           //

           // View Engine and related infrastructure

           //

           services.TryAddSingleton<ICompositeViewEngine, CompositeViewEngine>();

           services.TryAddSingleton<IActionResultExecutor<ViewResult>, ViewResultExecutor>();

           services.TryAddSingleton<IActionResultExecutor<PartialViewResult>, PartialViewResultExecutor>();

           // Support for activating ViewDataDictionary

           services.TryAddEnumerable(

               ServiceDescriptor

                   .Transient<IControllerPropertyActivator, ViewDataDictionaryControllerPropertyActivator>());

           //

           // HTML Helper

           //

           services.TryAddTransient<IHtmlHelper, HtmlHelper>();

           services.TryAddTransient(typeof(IHtmlHelper<>), typeof(HtmlHelper<>));

           services.TryAddSingleton<IHtmlGenerator, DefaultHtmlGenerator>();

           services.TryAddSingleton<ModelExpressionProvider>();

           // ModelExpressionProvider caches results. Ensure that it's re-used when the requested type is IModelExpressionProvider.

           services.TryAddSingleton<IModelExpressionProvider>(s => s.GetRequiredService<ModelExpressionProvider>());

           services.TryAddSingleton<ValidationHtmlAttributeProvider, DefaultValidationHtmlAttributeProvider>();

           services.TryAddSingleton<IJsonHelper, SystemTextJsonHelper>();

           // Component services for Blazor server-side interop

           services.TryAddSingleton<ServerComponentSerializer>();

           //

           // View Components

           //

           // These do caching so they should stay singleton

           services.TryAddSingleton<IViewComponentSelector, DefaultViewComponentSelector>();

           services.TryAddSingleton<IViewComponentFactory, DefaultViewComponentFactory>();

           services.TryAddSingleton<IViewComponentActivator, DefaultViewComponentActivator>();

           services.TryAddSingleton<

               IViewComponentDescriptorCollectionProvider,

               DefaultViewComponentDescriptorCollectionProvider>();

           services.TryAddSingleton<IActionResultExecutor<ViewComponentResult>, ViewComponentResultExecutor>();

           services.TryAddSingleton<ViewComponentInvokerCache>();

           services.TryAddTransient<IViewComponentDescriptorProvider, DefaultViewComponentDescriptorProvider>();

           services.TryAddSingleton<IViewComponentInvokerFactory, DefaultViewComponentInvokerFactory>();

           services.TryAddTransient<IViewComponentHelper, DefaultViewComponentHelper>();

           //

           // Temp Data

           //

           services.TryAddEnumerable(

               ServiceDescriptor.Transient<IApplicationModelProvider, TempDataApplicationModelProvider>());

           services.TryAddEnumerable(

               ServiceDescriptor.Transient<IApplicationModelProvider, ViewDataAttributeApplicationModelProvider>());

           services.TryAddSingleton<SaveTempDataFilter>();

           //

           // Component rendering

           //

           services.TryAddScoped<IComponentRenderer, ComponentRenderer>();

           services.TryAddScoped<StaticComponentRenderer>();

           services.TryAddScoped<NavigationManager, HttpNavigationManager>();

           services.TryAddScoped<IJSRuntime, UnsupportedJavaScriptRuntime>();

           services.TryAddScoped<INavigationInterception, UnsupportedNavigationInterception>();

           services.TryAddTransient<ControllerSaveTempDataPropertyFilter>();

           // This does caching so it should stay singleton

           services.TryAddSingleton<ITempDataProvider, CookieTempDataProvider>();

           services.TryAddSingleton<TempDataSerializer, DefaultTempDataSerializer>();

           //

           // Antiforgery

           //

           services.TryAddSingleton<ValidateAntiforgeryTokenAuthorizationFilter>();

           services.TryAddSingleton<AutoValidateAntiforgeryTokenAuthorizationFilter>();

           // These are stateless so their lifetime isn't really important.

           services.TryAddSingleton<ITempDataDictionaryFactory, TempDataDictionaryFactory>();

           services.TryAddSingleton(ArrayPool<ViewBufferValue>.Shared);

           services.TryAddScoped<IViewBufferScope, MemoryPoolViewBufferScope>();

       }

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找到了 services.TryAddSingleton<ITempDataDictionaryFactory, TempDataDictionaryFactory>();

这一段绑定的代码。