c# - 为什么 Entity Framework Core 迁移需要 .NET Core 2.x？

Question

在我的 .NET5.0 项目中，安装了 PostgreSQL Nuget 包( Npgsql.EntityFrameworkCore.PostgrSQL (5.0.2) )及其对 EF Core 的依赖( Microsoft.EntityFrameworkCore (5.0.2) )。
我正在尝试使用以下命令创建迁移:

dotnet ef migrations add InitialCreate

但是，迁移失败，因为我被要求安装 .NET Core 2.0.0 - 按照推荐的下载链接，我被告知它不再可用，我可能想要使用 5.0。我到底如何才能运行迁移？
这是输出的样子:

Build started...
Build succeeded.
It was not possible to find any compatible framework version
The framework 'Microsoft.NETCore.App', version '2.0.0' was not found.
  - The following frameworks were found:
      3.1.11 at [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
      3.1.12 at [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
      3.1.13 at [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
      5.0.3 at [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
      5.0.4 at [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

You can resolve the problem by installing the specified framework and/or SDK.

The specified framework can be found at:
  - https://aka.ms/dotnet-core-applaunch?framework=Microsoft.NETCore.App&framework_version=2.0.0&arch=x64&rid=osx.11.0-x64

Answer 1

确保您有 <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="5.0.5" />在您的 csproj 中。也尝试更新 dotnet-ef 工具:dotnet tool update --global dotnet-ef .
我执行了这些操作，问题就消失了。