添加迁移显示错误EntityFrameworkCore.Design未安装

Question

我在这里按照EntityFrameworkCore教程 https://docs.efproject.net/en/staging/platforms/aspnetcore/new-db.html 但是当我到达教程的创建数据库部分 https://docs.efproject .net/en/staging/platforms/aspnetcore/new-db.html #create-your-database 并运行命令Add-Migration MyFirstMigration我收到以下错误:

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.

我尝试安装Microsoft.EntityFrameworkCore.Design以及Microsoft.EntityFrameworkCore.SqlServer.Design NuGet上的每个版本但仍然得到相同的错误.

我还尝试使用该命令在NuGet PM之外运行

• dotnet恢复
• dotnet ef migrations添加MyFirstMigration

并得到以下错误:

Unhandled Exception: System.MissingMethodException: Entry point not found in assembly 'Microsoft.EntityFrameworkCore.Design, Version=1.1.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'.

我尝试了所有我能想到的东西,并在互联网上到处寻找,但仍然没有找到答案.

Answer 1

检查您的project.json是否包含这些条目

在依赖项下:

"Microsoft.EntityFrameworkCore.Design": {
  "version": "1.0.0-preview2-final",
  "type": "build"
},

"Microsoft.EntityFrameworkCore.SqlServer": "1.0.1",

在工具下:

"Microsoft.EntityFrameworkCore.Tools": {
  "version": "1.0.0-preview2-final",
  "imports": [
    "portable-net45+win8+dnxcore50",
    "portable-net45+win8"
  ]
},