无法解析类型为"Microsoft.Extensions.Logging.ILogger`1 [WebApplication1.Startup]"的服务 [英] Unable to resolve service for type 'Microsoft.Extensions.Logging.ILogger`1[WebApplication1.Startup]'

问题描述

我在Visual Studio 2019 Preview 2.2中使用默认模板创建了ASP.NET Core 3.0 Web应用程序，并尝试在启动时注入ILogger:

I created an ASP.NET Core 3.0 Web Application with the default template in Visual Studio 2019 Preview 2.2 and tried to inject an ILogger in Startup:

namespace WebApplication1
{
    public class Startup
    {
        private readonly ILogger _logger;

        public Startup(IConfiguration configuration, ILogger<Startup> logger)
        {
            Configuration = configuration;
            _logger = logger;
        }
        // ...
    }
}

在Program.cs中，我还调用了ConfigureLogging()方法:

In Program.cs I also call the ConfigureLogging() method:

namespace WebApplication1
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureLogging((hostingContext, logging) =>
                {
                    logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
                    logging.ClearProviders();
                    logging.AddConsole();
                })
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });
    }
}

它在ASP.NET Core 2.x中工作，但在ASP.NET Core 3中失败，并出现以下错误:

It works in ASP.NET Core 2.x but in ASP.NET Core 3 it fails with the following error:

System.InvalidOperationException: Unable to resolve service for type 'Microsoft.Extensions.Logging.ILogger`1[WebApplication1.Startup]' while attempting to activate 'WebApplication1.Startup'.
   at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ConstructorMatcher.CreateInstance(IServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.CreateInstance(IServiceProvider provider, Type instanceType, Object[] parameters)
   at Microsoft.AspNetCore.Hosting.Internal.GenericWebHostBuilder.UseStartup(Type startupType, HostBuilderContext context, IServiceCollection services)
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Hosting.Internal.GenericWebHostBuilder.<>c__DisplayClass13_0.<UseStartup>b__2(IApplicationBuilder app)
   at Microsoft.AspNetCore.Server.IIS.Core.IISServerSetupFilter.<>c__DisplayClass2_0.<Configure>b__0(IApplicationBuilder app)
   at Microsoft.AspNetCore.HostFilteringStartupFilter.<>c__DisplayClass0_0.<Configure>b__0(IApplicationBuilder app)
   at Microsoft.AspNetCore.Hosting.Internal.GenericWebHostService.StartAsync(CancellationToken cancellationToken)

关于导致此行为的原因有什么想法?

Any idea on what is causing this behavior?

在默认的"Web应用程序"模板的完整Program.cs和Startup.cs文件下面，仅添加了日志记录.

Below the full Program.cs and Startup.cs files from the default "Web Application" template, only logging was added.

Program.cs

Program.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace WebApplication1
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureLogging((hostingContext, logging) =>
                {
                    logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
                    logging.ClearProviders();
                    logging.AddConsole();
                })
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });
    }
}

Startup.cs

Startup.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

namespace WebApplication1
{
    public class Startup
    {
        private readonly ILogger _logger;
        public Startup(IConfiguration configuration, ILogger<Startup> logger)
        {
            Configuration = configuration;
            _logger = logger;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.Configure<CookiePolicyOptions>(options =>
            {
                // This lambda determines whether user consent for non-essential cookies is needed for a given request.
                options.CheckConsentNeeded = context => true;
                options.MinimumSameSitePolicy = SameSiteMode.None;
            });

            //services.AddTransient(typeof(ILogger<>), (typeof(Logger<>)));

            services.AddMvc()
                .AddNewtonsoftJson();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting(routes =>
            {
                routes.MapApplication();
            });

            app.UseCookiePolicy();

            app.UseAuthorization();
        }
    }
}

推荐答案

不幸的是，再也无法将ILogger注入ASP.NET Core 3.0中的Startup.cs中.

Unfortunately, it's not possible to inject ILogger into Startup.cs in ASP.NET Core 3.0 anymore.

注意

在ASP.NET Core 3.0和更高版本中，不再可能注入 Startup.cs和Program.cs中的ILogger.看 https://github.com/aspnet/Announcements/issues/353 了解更多详细信息.

In ASP.NET Core 3.0 and later, it is no longer possible to inject ILogger in Startup.cs and Program.cs. See https://github.com/aspnet/Announcements/issues/353 for more details.

这篇关于无法解析类型为"Microsoft.Extensions.Logging.ILogger`1 [WebApplication1.Startup]"的服务的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！