如何在 asp.net core 1.1 中更新现有的 dbcontext

Question

我使用下面的命令来创建 dbcontext

Scaffold-DbContext "Data Source=SANPC;Initial Catalog=EMAKITI;Trusted_Connection=True;" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Data

以上命令成功创建了包含所有表的dbcontext。

现在，我已经更改了表格的某些列并使用以下命令进行更新

Scaffold-DbContext -Connection "Data Source=SANPC;Initial Catalog=EMAKITI;Integrated Security=True;Trusted_Connection=True;" -Provider Microsoft.EntityFrameworkCore.SqlServer -OutputDir Entity -context EmakitiContext -Project DataBase -force

上面的命令给我一个错误

指定的deps.json [D:\GitAlpha\eMikitiWebApi\eMikitiWebApiPortal\src\eMikitiWebApiPortal\bin\Debug\netcoreapp1.1\eMikitiWebApiPortal.deps.json] 不存在 进程以非零退出代码结束

我做了很多研究。无法解决这个问题。我使用的是 asp.net core 1.1

这里是 project.json 文件

    {
  "dependencies": {
    "Microsoft.Extensions.Logging": "1.1.0",
    "Microsoft.EntityFrameworkCore.SqlServer": "1.1.0",
    "Microsoft.EntityFrameworkCore.Tools": "1.1.0-preview4-final",
    "Microsoft.EntityFrameworkCore.Design": "1.1.0",
    "Microsoft.EntityFrameworkCore.SqlServer.Design": "1.1.0",
    "DataBase": "1.0.0-*",
    "UnitOfWork": "1.0.0-*",
    "ViewModel": "1.0.0-*",
    "Common": "1.0.0-*",
    "Microsoft.AspNetCore.Session": "1.1.0",
    "Microsoft.Extensions.Caching.Memory": "1.1.0",
    "Microsoft.Extensions.Options.ConfigurationExtensions": "1.1.0",
    "Microsoft.NETCore.App": "1.1.0",
    "System.IdentityModel.Tokens.Jwt": "5.1.2",
    "Microsoft.AspNetCore.Authentication.JwtBearer": "1.1.0",
    "Microsoft.AspNetCore.Diagnostics": "1.1.0",
    "Microsoft.AspNetCore.Mvc": "1.1.0",
    "Microsoft.AspNetCore.Routing": "1.1.0",
    "Microsoft.AspNetCore.Server.IISIntegration": "1.1.0",
    "Microsoft.AspNetCore.Server.Kestrel": "1.1.0",
    "Microsoft.AspNetCore.StaticFiles": "1.1.0",
    "Microsoft.Extensions.Configuration.EnvironmentVariables": "1.1.0",
    "Microsoft.Extensions.Configuration.FileExtensions": "1.1.0",
    "Microsoft.Extensions.Configuration.Json": "1.1.0",
    "Microsoft.Extensions.Logging.Console": "1.1.0",
    "Microsoft.Extensions.Logging.Debug": "1.1.0",
    "Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore": "1.1.0"
  },

  "tools": {
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final",
    "Microsoft.EntityFrameworkCore.Tools.DotNet": "1.0.0-preview3-final",
    "Microsoft.AspNetCore.Razor.Tools": "1.0.0-preview2-final"
  },

  "frameworks": {
    "netcoreapp1.1": {
      "imports": [
        "dotnet5.6",
        "portable-net45+win8"
      ]
    }
  },
  "runtimes": {
    "win10-x64": {}
  },

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

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

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

  "scripts": {
    "postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ]
  }
}

Answer 1

您正在使用代码优先方法，并且在这种方法中，更改从代码流向数据库。实体框架让我们可以选择从现有数据库开始进行逆向工程。当我们进行一次逆向工程来生成我们的模型时，之后我们需要遵循代码优先方法代码到数据库的迁移流程。

使用这个命令我们生成迁移

dotnet ef migrations add InitialCreate -c SchoolContext

然后我们将它应用到数据库中。

dotnet ef database update -c SchoolContext

你可以了解更多关于这个here