我是新的EF核心,我试图让它与我的ASP工作。NET Core项目。

当我尝试配置DbContext使用config中的连接字符串时,我在startup.cs中得到了上述错误。我正在遵循这个教程。

有问题的代码在startup.cs中:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.SpaServices.Webpack;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.EntityFrameworkCore;
using tracV2.models;
using tracV2.data;

namespace tracV2
{
    public class Startup
    {
        // 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.AddSingleton<IConfiguration>(Configuration);

            string conn = Configuration.GetConnectionString("optimumDB");

            services.AddDbContext<tracContext>(options => options.usesqlserver(conn));
        }

如果我把UseSqlServer方法直接放到上下文中,它就会被识别出来:

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

namespace tracV2.data
{
    public class tracContext : DbContext
    {
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlServer("myrealconnectionstring");
        }

我在网上的所有研究都指向了缺失的参考文献,但我似乎找不到我缺失的是哪一本(见图)。


当前回答

我也有同样的问题。我添加了以下内容。这对我很有用

Microsoft.EntityFrameworkCore.SqlServer

其他回答

当我转移到Microsoft.EntityFrameworkCore.SqlServer v3.0.0和Microsoft.EntityFrameworkCore.Tools v3.0.0时,我遇到了这个问题

当我在两个库上都改回v2.2.6时,错误就消失了。这更像是一种变通方法而不是解决方案,但它会让你启动并运行,直到问题得到解决。

我相信这个问题可以通过在Microsoft.EntityFrameworkCore.SqlServer.Design中添加项目引用来解决

Install-Package Microsoft.EntityFrameworkCore.SqlServer.Design

sqlserver没有直接安装在我的项目中,但是. design包将作为先决条件安装它。

添加 使用Microsoft.EntityFrameworkCore;

手动解决了我的问题

在这里找到

编辑……

为dotnet核心3.1添加

Microsoft.EntityFrameworkCore.SqlServer

I had same issue but problem went off after going back and fixing DbContext incorrect syntax issue such as it should have been ExampleDbContextClass: DbContext whereas I had missed DbContext part in Context Class where you define your DbSet. Also, I verified following dependencies are needed in order to achieve connection to SqlServer. <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="3.1.0" /> <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer.Design" Version="1.1.6" /> Also verify that Version you install is less than your project's current version to be on safe side. Such as if your project is using 3.1 do not try to use newer one which would be for example 3.1.9. I had issue with that too.

我添加SqlServer和Sqlite到我的项目,同样的问题出现了。

对我来说,我安装了微软。EntityFrameworkCore之前的版本是5.0.6。现在Microsoft.EntityFrameworkCore.SqlServer的版本是5.0.7。安装后没有UserSqlServer方法。

1. 请尝试升级工具版本以保持一致

尝试在csproj中修改版本:

<PackageReference Include="Microsoft.EntityFrameworkCore" Version="5.0.7">

或者打开NuGet来更新包。

2. 重新启动Visual Studio

如果它不能帮助你,最重要的是重新启动VS

然后,一切都好了。

参考 https://github.com/dotnet/efcore/issues/7891