为什么 add-migration 命令不创建迁移？无法识别包裹答案

【问题标题】：Why add-migration command is not creating migration? Not recognising packages为什么 add-migration 命令不创建迁移？无法识别包裹
【发布时间】：2017-04-03 13:28:00
【问题描述】：

安装以下软件包后：

"Microsoft.EntityFrameworkCore.SqlServer": "1.1.0", "Microsoft.EntityFrameworkCore.Tools": "1.1.0-preview4-final" (-Pre)

运行add-migration "InitialCreate" 命令时，出现以下错误：

Cannot execute this command because Microsoft.EntityFrameworkCore.Design is not installed. Install the version of that package that matches the installed version of Microsoft.EntityFrameworkCore and try again. 但是，如果您查看下面的.json 文件，您会看到包是匹配的，所以这个错误消息与我相矛盾。

这是我的project.json 文件：

{
  "runtimes": {
    "win10-x64": {}
  },

  "dependencies": {
    "Microsoft.AspNetCore.Diagnostics": "1.1.0",
    "Microsoft.AspNetCore.Mvc": "1.1.0",
    "Microsoft.AspNetCore.Server.IISIntegration": "1.1.0",
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final",
    "Microsoft.AspNetCore.Server.Kestrel": "1.1.0",
    "Microsoft.AspNetCore.StaticFiles": "1.1.0",
    "Microsoft.EntityFrameworkCore": "1.1.0",
    "Microsoft.EntityFrameworkCore.Design": "1.1.0",
    "Microsoft.EntityFrameworkCore.SqlServer": "1.1.0",
    "Microsoft.EntityFrameworkCore.Tools": "1.1.0-preview4-final",
    "Microsoft.Extensions.Configuration.FileExtensions": "1.1.0",
    "Microsoft.Extensions.Configuration.Json": "1.1.0",
    "Microsoft.Extensions.Logging.Console": "1.1.0",
    "Microsoft.NETCore.App": "1.1.0"
  },

  "tools": {
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview2-final",
    "Microsoft.EntityFrameworkCore.Tools": "1.1.0-preview4-final"
  },

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

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

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

  "publishOptions": {
    "include": [
      "wwwroot",
      "web.config"
    ]
  },

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

【问题讨论】：

标签： c# asp.net entity-framework visual-studio entity-framework-core

【解决方案1】：

您需要更改您的project.json，如下所示。

注意：需要包含"type": "platform"

{
  "dependencies": {
    "Microsoft.NETCore.App": {
      "version": "1.0.1",
      "type": "platform"
    }
  }
}

您可以在此处阅读有关此问题的更多信息：GitHub

【讨论】：

【解决方案2】：

如果您的解决方案中有多个项目。使用 -projectname 选择合适的项目，像这样

添加迁移 InitialCreate -ProjectName mydbProject

将 mydbProject 替换为您的项目名称

【讨论】：