如何在ASP.NET Core 1.0的DI中的Startup类中添加IHttpContextAccessor? [英] How to add IHttpContextAccessor in the Startup class in the DI in ASP.NET Core 1.0?

问题描述

在ASP.NET Core RC 1中，我使用以下代码来检索context的值(页面的完整地址).然后，我将此值记录在配置中.

In ASP.NET Core RC 1 I used the following code to retrieve the value of context (full address of the page). Then I recorded this value in the configuration.

public class Startup
{
        public IConfigurationRoot Configuration { get; set; }
        private IHostingEnvironment CurrentEnvironment { get; set; }
        private IHttpContextAccessor HttpContextAccessor { get; set; }
        public Startup(IHostingEnvironment env,
                IHttpContextAccessor httpContextAccessor)
            {                
                var builder = new ConfigurationBuilder()
                    .SetBasePath(env.ContentRootPath)
                    .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                    .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true);
    
                if (env.IsDevelopment())
                {
                    builder.AddUserSecrets();
                }
                builder.AddEnvironmentVariables();
                Configuration = builder.Build();
                CurrentEnvironment = env;
                HttpContextAccessor = httpContextAccessor;
            }
        public void ConfigureServices(IServiceCollection services)
        {
        ...
        
        services.AddOptions();
        services.Configure<WebAppSettings>(configuration);
        services.Configure<WebAppSettings>(settings =>
        {
            ...
            settings.WebRootPath = CurrentEnvironment.WebRootPath;
            settings.DomainUrl = HttpContextAccessor.HttpContext.Request.Host.ToUriComponent();
        });
        }
   }

现在，我开始在ASP.NET Core 1.0上更新项目.但是在网站启动期间，出现以下错误:

Now I started to update the project on ASP.NET Core 1.0. But during the launch of the site I get the following error:

System.InvalidOperationException无法解析类型的服务 尝试执行'Microsoft.AspNetCore.Http.IHttpContextAccessor' 激活"MyProject.Startup".

System.InvalidOperationException Unable to resolve service for type 'Microsoft.AspNetCore.Http.IHttpContextAccessor' while attempting to activate 'MyProject.Startup'.

在 Microsoft.Extensions.Internal.ConstructorMatcher.CreateInstance(IServiceProvider 供应商) Microsoft.Extensions.Internal.ActivatorUtilities.CreateInstance(IServiceProvider 提供者，类型为instanceType，Object []参数)位于 Microsoft.Extensions.Internal.ActivatorUtilities.GetServiceOrCreateInstance(IServiceProvider 提供者，类型类型)在 Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetServiceOrCreateInstance(IServiceProvider 提供者，类型类型)在 Microsoft.AspNetCore.Hosting.Internal.StartupLoader.LoadMethods(IServiceProvider 服务，键入startupType，字符串environmentName)，位于 Microsoft.AspNetCore.Hosting.<> c__DisplayClass1_0.b__1(IServiceProvider sp)在 Microsoft.Extensions.DependencyInjection.ServiceLookup.FactoryService.Invoke(ServiceProvider 供应商) Microsoft.Extensions.DependencyInjection.ScopedCallSite.Invoke(ServiceProvider 供应商) Microsoft.Extensions.DependencyInjection.SingletonCallSite.Invoke(ServiceProvider 供应商) Microsoft.Extensions.DependencyInjection.<> c__DisplayClass12_0.b__0(ServiceProvider 供应商) Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType)在 Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider 提供者，键入serviceType)，位于 Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider 供应商) Microsoft.AspNetCore.Hosting.Internal.WebHost.EnsureStartup()在 Microsoft.AspNetCore.Hosting.Internal.WebHost.EnsureApplicationServices() 在Microsoft.AspNetCore.Hosting.Internal.WebHost.BuildApplication()

at Microsoft.Extensions.Internal.ConstructorMatcher.CreateInstance(IServiceProvider provider) at Microsoft.Extensions.Internal.ActivatorUtilities.CreateInstance(IServiceProvider provider, Type instanceType, Object[] parameters) at Microsoft.Extensions.Internal.ActivatorUtilities.GetServiceOrCreateInstance(IServiceProvider provider, Type type) at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetServiceOrCreateInstance(IServiceProvider provider, Type type) at Microsoft.AspNetCore.Hosting.Internal.StartupLoader.LoadMethods(IServiceProvider services, Type startupType, string environmentName) at Microsoft.AspNetCore.Hosting.<>c__DisplayClass1_0.b__1(IServiceProvider sp) at Microsoft.Extensions.DependencyInjection.ServiceLookup.FactoryService.Invoke(ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ScopedCallSite.Invoke(ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.SingletonCallSite.Invoke(ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.<>c__DisplayClass12_0.b__0(ServiceProvider provider) at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType) at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType) at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider) at Microsoft.AspNetCore.Hosting.Internal.WebHost.EnsureStartup() at Microsoft.AspNetCore.Hosting.Internal.WebHost.EnsureApplicationServices() at Microsoft.AspNetCore.Hosting.Internal.WebHost.BuildApplication()

.NET Framework X64 v4.0.30319.42000 | Microsoft.AspNetCore.Hosting 版本1.0.0-rtm-21431 | Microsoft Windows 6.1.7601 S

.NET Framework X64 v4.0.30319.42000 | Microsoft.AspNetCore.Hosting version 1.0.0-rtm-21431 | Microsoft Windows 6.1.7601 S

在应用程序启动期间如何获取新版本的IHttpContextAccessor?

How do I get the new version IHttpContextAccessor during application startup?

推荐答案

它不再是默认服务.您必须在Startup.cs中配置它

It is no longer a default service. You have to configure it in Startup.cs

services.TryAddSingleton<IHttpContextAccessor, HttpContextAccessor>();
services.TryAddSingleton<IActionContextAccessor, ActionContextAccessor>();

更新:在ASP.NET Core 2.1中， AddHttpContextAccessor添加了辅助程序扩展方法以正确注册具有正确生命周期(单身)的IHttpContextAccessor.因此，在ASP.NET Core 2.1及更高版本中，代码应为

UPDATE: In ASP.NET Core 2.1, the AddHttpContextAccessor helper extension method was added to correctly register the IHttpContextAccessor with the correct lifetime (singleton). So, in ASP.NET Core 2.1 and above, the code should be

services.AddHttpContextAccessor();
services.TryAddSingleton<IActionContextAccessor, ActionContextAccessor>();

来源: https://github.com/aspnet/Hosting/issues/793

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