EntityFramework Core不使用"EDMX"数据模型设计器，它纯粹是代码优先的.

EntityFramework Core doesn't use the "EDMX" data model designers, it is purely code-first.

请参见 EF Core入门具有现有数据库的ASP.NET Core ，可以从现有数据库中构建数据库上下文，或者创建新模型，并使用迁移来创建和更新数据库.

See the Getting Started with EF Core on ASP.NET Core with an Existing Database to scaffold a database context from an existing database or create a new model and use migrations to create and update databases.

更新:在.NET Core 3.0中，您将能够将Entity Framework 6与.edmx模型一起使用(可能需要VS 2019)

Update: In .NET Core 3.0, you will be able to use Entity Framework 6 along with .edmx models (which may require VS 2019)