C# “启用迁移”在Package Manager控制台中不起作用

C# “启用迁移”在Package Manager控制台中不起作用,c#,visual-studio,entity-framework,nuget-package,C#,Visual Studio,Entity Framework,Nuget Package,我在我的解决方案中安装了EF: PM> Install-Package EntityFramework -IncludePrerelease 之后,我尝试执行enable migration命令,但它不起作用: PM> enable-migrations 错误: No context type was found in the assembly 'MyProjectName'. 从下拉菜单“默认项目”中指定具有DbContext派生类的目标项目,或者: PM>启用迁移-项目 您

我在我的解决方案中安装了EF:

PM> Install-Package EntityFramework -IncludePrerelease
之后,我尝试执行enable migration命令,但它不起作用:

PM> enable-migrations
错误:

No context type was found in the assembly 'MyProjectName'.

从下拉菜单“默认项目”中指定具有DbContext派生类的目标项目,或者:

PM>启用迁移-项目


您应该向项目中添加上下文类。类似于公共类MyContext:DbContext。的可能重复项