Question

我一直在努力将我的上下文类注入我的应用程序而没有任何成功。

为什么我创建的dbcontext类必须是通用类型？或者我做错了什么？谢谢。

Startup.cs：

    using Microsoft.AspNetCore.Builder;
    using Microsoft.AspNetCore.Hosting;
    using Microsoft.Extensions.Configuration;
    using Microsoft.Extensions.DependencyInjection;
    using Microsoft.Extensions.Logging;
    using Car_proj_new.Models;
    using Microsoft.Data.Entity;


    namespace Car_proj_new
    {
        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();
                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.

                var connection = Configuration["Data:ConnectionString"];

                services.AddEntityFramework().AddDbContext<CarDbContext>( options => { options.UseSqlServer(connection); });




                services.AddMvc();
            }
            // 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();

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

                app.UseStaticFiles();

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

Db上下文类：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;

namespace Car_proj_new.Models
{
    public class CarDbContext: DbContext
    {

        public DbSet<Corporations> Corporations { get; set; }
        public DbSet<PossibleFixes> PossibleFixes { get; set; }
        public DbSet<Workers> Workers { get; set; }

    }
}

Project.Json：

{
  "dependencies": {
    "EntityFramework.Core": "7.0.0-rc1-final",
    "EntityFramework.MicrosoftSqlServer": "7.0.0-rc1-final",
    "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.AspNetCore.Server.IISIntegration": "1.0.0",
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.0",
    "Microsoft.AspNetCore.StaticFiles": "1.0.0",
    "Microsoft.EntityFrameworkCore": "1.0.0",
    "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final",
    "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"
  },

  "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"
  },

  "frameworks": {
    "netcoreapp1.0": {
      "imports": [
        "dotnet5.6",
        "dnxcore50",
        "portable-net45+win8"
      ]
    }
  },

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

错误：

错误CS0311类型'Car_proj_new.Models.CarDbContext'不能用作泛型类型或方法'EntityFrameworkServicesBuilder.AddDbContext（Action）'中的类型参数'TContext'。没有从'Car_proj_new.Models.CarDbContext'到'Microsoft.Data.Entity.DbContext'的隐式引用转换。 Car_proj_new..NETCoreApp，版本= 1.0

错误似乎很简单，但我无法理解，我很感激你的答案。

Answer 1

这里没有代码，我可以说请检查以下内容 1）Name spaces - 如果您的上下文类位于类库中，请检查项目是否已添加为引用（project.json） 2）看起来您正在引用EF核心 - 我的 * guess * 但生成的上下文类来自或使用full .net framework

这是一个示例

using Microsoft.EntityFrameworkCore;

services.AddDbContext<MyContext>(options => { options.UseSqlServer(connection); });

{
    "dependencies": {
    "Microsoft.EntityFrameworkCore.SqlServer": "1.0.0",
    "Microsoft.EntityFrameworkCore": "1.0.0",
    "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final",
  },
  "frameworks": {
    "netcoreapp1.0": {
      "imports": [
        "dotnet5.6",
        "dnxcore50",
        "portable-net45+win8"
      ]
    }
  }
}

以上对我有用。技术堆栈.net core和EF Core

Answer 2

将此代码添加到您的CarDbContext中：

namespace Car_proj_new.Models
{
   public class CarDbContext: DbContext
   {
      //***
      public CarDbContext(DbContextOptions<CarDbContext> options) : base (options)
       {
       }
      //***
      public DbSet<Corporations> Corporations { get; set; }
      public DbSet<PossibleFixes> PossibleFixes { get; set; }
      public DbSet<Workers> Workers { get; set; }

   }
}

配置实体框架/ DbContext

2 个答案: