C# 无法加载类型ServiceCollectionExtensions

我正在使用ASP.NET Core 1.0并尝试为迁移配置我的DbContext。我得到了一个例外：

无法从程序集“Microsoft.Extensions.DependencyInjection.Abstractions，Version=1.0.0.0，Culture=neutral，PublicKeyToken=adb9793829ddae60”加载类型“Microsoft.Extensions.DependencyInjection.Extensions.ServiceCollectionExtensions”

我不知道为什么会出现这个错误。有人知道我错过了什么吗

project.json

{
  "dependencies": {
    "Microsoft.NETCore.App": {
      "version": "1.0.0",
      "type": "platform"
    },
    "Microsoft.ApplicationInsights.AspNetCore": "1.0.0",
    "Microsoft.AspNetCore.Diagnostics": "1.0.0",
    "Microsoft.AspNetCore.Mvc": "1.0.0",
    "Microsoft.AspNetCore.Razor.Tools": {
      "version": "1.0.0-preview2-final",
      "type": "build"
    },
    "Microsoft.EntityFrameworkCore.Design": {
      "type": "build",
      "version": "1.0.0-preview2-final"
    },
    "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0",
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.0",
    "Microsoft.AspNetCore.StaticFiles": "1.0.0",
    "Microsoft.Extensions.Configuration.EnvironmentVariables": "1.0.0",
    "Microsoft.Extensions.Configuration.Json": "1.0.0",
    "Microsoft.Extensions.Logging": "1.0.0",
    "Microsoft.Extensions.Logging.Console": "1.0.0",
    "Microsoft.Extensions.Logging.Debug": "1.0.0",
    "Microsoft.Extensions.Options.ConfigurationExtensions": "1.0.0",
    "Microsoft.VisualStudio.Web.BrowserLink.Loader": "14.0.0",
    "Microsoft.EntityFrameworkCore.SqlServer": "1.0.0-rc2-final",
    "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview1-final",
  },

  "tools": {
    "BundlerMinifier.Core": "2.0.238",
    "Microsoft.AspNetCore.Razor.Tools": "1.0.0-preview2-final",
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final",
    "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final"
  },

  "frameworks": {
    "netcoreapp1.0": {
      "imports": [
        "dotnet5.6",
        "portable-net45+win8"
      ]
    }
  },

  "buildOptions": {
    "emitEntryPoint": true,
    "preserveCompilationContext": true
  },

  "runtimeOptions": {
    "configProperties": {
      "System.GC.Server": true
    }
  },

  "publishOptions": {
    "include": [
      "wwwroot",
      "Views",
      "Areas/**/Views",
      "appsettings.json",
      "web.config"
    ]
  },

  "scripts": {
    "prepublish": [ "bower install", "dotnet bundle" ],
    "postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ]
  }
}

Startup.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using OdeToFood.Services;
using OdeToFood.Entities;
using Microsoft.EntityFrameworkCore;

namespace OdeToFood
{
    public class Startup
    {
        public Startup(IHostingEnvironment env)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
                .AddEnvironmentVariables();

            if (env.IsDevelopment())
            {
                // This will push telemetry data through Application Insights pipeline faster, allowing you to view results immediately.
                builder.AddApplicationInsightsSettings(developerMode: true);
            }
            Configuration = builder.Build();
        }

        public IConfigurationRoot Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            // Add framework services.

            services.AddMvc();

            services.AddEntityFrameworkSqlServer()
                .AddDbContext<OdeToFoodDbContext>(options => options.UseSqlServer("@Server = (localdb)\\MSSQLLocalDB; Database = OdeToFood; Trusted_Connection = True; MultipleActiveResultSets = true"));
            services.AddSingleton(provider => Configuration);
            services.AddApplicationInsightsTelemetry(Configuration);
            services.AddScoped<IRestaurantData, InMemoryRestaurantData> ();

        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();

            app.UseApplicationInsightsRequestTelemetry();

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseBrowserLink();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }

            app.UseApplicationInsightsExceptionTelemetry();

            app.UseStaticFiles();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}

using Microsoft.EntityFrameworkCore;

namespace OdeToFood.Entities
{
    public class OdeToFoodDbContext:DbContext
    {
        public DbSet<Restaurant> Restaurants { get; set; }

        //protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        //{
        //    optionsBuilder.UseSqlServer("@Server = (localdb)\\MSSQLLocalDB; Database = OdeToFood; Trusted_Connection = True; MultipleActiveResultSets = true");
        //}
    }
}

使用Microsoft.AspNetCore.Builder；
使用Microsoft.AspNetCore.Hosting；
使用Microsoft.Extensions.Configuration；
使用Microsoft.Extensions.DependencyInjection；
使用Microsoft.Extensions.Logging；
使用OdeToFood.Services；
使用OdeToFood.实体；
使用Microsoft.EntityFrameworkCore；
木薯
{
公营创业
{
公共启动（IHostingEnvironment环境）
{
var builder=new ConfigurationBuilder（）
.SetBasePath（env.ContentRootPath）
.AddJsonFile（“appsettings.json”，可选：true，重载更改：true）
.AddJsonFile（$“appsettings.{env.EnvironmentName}.json”，可选：true）
.AddenEnvironmentVariables（）；
if（env.IsDevelopment（））
{
//这将使遥测数据更快地通过Application Insights管道，从而允许您立即查看结果。
AddApplicationInsightsSettings（developerMode:true）；
}
Configuration=builder.Build（）；
}
公共IConfigurationRoot配置{get；}
//此方法由运行时调用。请使用此方法将服务添加到容器中。
public void配置服务（IServiceCollection服务）
{
//添加框架服务。
services.AddMvc（）；
services.AddEntityFrameworkSqlServer（）
.AddDbContext（options=>options.UseSqlServer（@Server=（localdb）\\MSSQLLocalDB；Database=OdeToFood；Trusted_Connection=True；MultipleActiveResultSets=True））；
AddSingleton（provider=>Configuration）；
services.AddApplicationInsightsTelemetry（配置）；
services.AddScoped（）；
}
//此方法由运行时调用。请使用此方法配置HTTP请求管道。
公共void配置（IApplicationBuilder应用程序、IHostingEnvironment环境、iLogger工厂）
{
loggerFactory.AddConsole（Configuration.GetSection（“Logging”）；
loggerFactory.AddDebug（）；
app.UseApplicationInsightsRequestTelemetry（）；
if（env.IsDevelopment（））
{
app.UseDeveloperExceptionPage（）；
app.UseBrowserLink（）；
}
其他的
{
app.UseExceptionHandler（“/Home/Error”）；
}
app.UseApplicationInsightsExceptionTelemetry（）；
app.UseStaticFiles（）；
app.UseMvc（路由=>
{
routes.MapRoute(
名称：“默认”，
模板：“{controller=Home}/{action=Index}/{id？}”）；
});
}
}
}

dbContext.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using OdeToFood.Services;
using OdeToFood.Entities;
using Microsoft.EntityFrameworkCore;

namespace OdeToFood
{
    public class Startup
    {
        public Startup(IHostingEnvironment env)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
                .AddEnvironmentVariables();

            if (env.IsDevelopment())
            {
                // This will push telemetry data through Application Insights pipeline faster, allowing you to view results immediately.
                builder.AddApplicationInsightsSettings(developerMode: true);
            }
            Configuration = builder.Build();
        }

        public IConfigurationRoot Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            // Add framework services.

            services.AddMvc();

            services.AddEntityFrameworkSqlServer()
                .AddDbContext<OdeToFoodDbContext>(options => options.UseSqlServer("@Server = (localdb)\\MSSQLLocalDB; Database = OdeToFood; Trusted_Connection = True; MultipleActiveResultSets = true"));
            services.AddSingleton(provider => Configuration);
            services.AddApplicationInsightsTelemetry(Configuration);
            services.AddScoped<IRestaurantData, InMemoryRestaurantData> ();

        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();

            app.UseApplicationInsightsRequestTelemetry();

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseBrowserLink();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }

            app.UseApplicationInsightsExceptionTelemetry();

            app.UseStaticFiles();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}

using Microsoft.EntityFrameworkCore;

namespace OdeToFood.Entities
{
    public class OdeToFoodDbContext:DbContext
    {
        public DbSet<Restaurant> Restaurants { get; set; }

        //protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        //{
        //    optionsBuilder.UseSqlServer("@Server = (localdb)\\MSSQLLocalDB; Database = OdeToFood; Trusted_Connection = True; MultipleActiveResultSets = true");
        //}
    }
}

使用Microsoft.EntityFrameworkCore；
名称空间OdeToFood.Entities
{
公共类OdeToFoodbContext:DbContext
{
公共DbSet餐厅{get；set；}
//配置时受保护的覆盖无效（DBContextOptions Builder Options Builder）
//{
//optionsBuilder.UseSqlServer（@Server=（localdb）\\MSSQLLocalDB；Database=OdeToFood；Trusted_Connection=True；MultipleActiveResultSets=True）；
//}
}
}

您的project.json正在引用此包的旧版本：

"Microsoft.EntityFrameworkCore.SqlServer": "1.0.0-rc2-final"

应该是：

"Microsoft.EntityFrameworkCore.SqlServer": "1.0.0"