EF Core 1.1 迁移 - 当前的 CSharpHelper 无法构建类型的文字 [英] EF Core 1.1 Migration - The current CSharpHelper cannot scaffold literals of type

问题描述

这似乎是一个非常晦涩的错误，我什至不知道从哪里开始......

<块引用>

当前的 CSharpHelper 不能为类型的字面量提供脚手架'System.Func`3[Microsoft.EntityFrameworkCore.Metadata.IProperty,Microsoft.EntityFrameworkCore.Metadata.IEntityType,Microsoft.EntityFrameworkCore.ValueGeneration.ValueGenerator]'.配置您的服务以使用可以使用的服务.

这是我跑步时发生的

dotnet ef 迁移添加初始

更新 1 - 基于 Rob 的问题

该应用程序的架构使用了丰富的域模型，因此有一些变通方法"可以使封装集合和 Jimmy Bogard 的类型化枚举模式发挥作用.

每个领域模型对象在数据访问层都有自己的EntityTypeBuilder类，所有这些类都是从DbContext中的OnModelCreating调用的.这些还向 Console 输出了一些信息，因此我可以看到构建器没有引起任何错误(此时都没有).

DbContext 只为聚合根实体公开 DbSet，或者换句话说，只有具有相应存储库类的实体.域模型对象的其余部分是导航属性，因此不需要通过 DbContext 公开 DbSet.

平台细节(据我所知)

• .NET Core 1.1(运行时 + SDK)
• EF 核心 1.1
• Microsoft.EntityFrameworkCore.Tools 1.0.0-preview2-final
• Microsoft.EntityFrameworkCore.Design 1.0.0-preview2-final

解决方案

您使用的是 .NET Core 1.1 运行时但旧的工具包(您应该使用最新的工具，截至今天它是 preview4，仍处于 alpha 阶段，与运行时相反 - 是的，一开始不是很直观)

总而言之，这是一个

This seems to be a really obscure error, and I don't even know where to start with it...

The current CSharpHelper cannot scaffold literals of type 'System.Func`3[Microsoft.EntityFrameworkCore.Metadata.IProperty,Microsoft.EntityFrameworkCore.Metadata.IEntityType,Microsoft.EntityFrameworkCore.ValueGeneration.ValueGenerator]'. Configure your services to use one that can.

This is occurring when I run

dotnet ef migrations add initial

Update 1 - based on Rob's question

The architecture of the application uses a rich domain model, so there are a few "workarounds" to get things like encapsulated collections, and Jimmy Bogard's typed enumeration pattern working.

Each domain model object has it's own EntityTypeBuilder class in the data access layer, all of which are called from OnModelCreating in the DbContext. These also output some information to the Console, so I can see that the builder isn't causing any errors (none of them are at this point).

The DbContext only exposes DbSet for aggregate root entities, or to put it another way, only entities that have a corresponding repository class. The rest of the domain model objects are navigation properties, and therefore do not require DbSet to be exposed via the DbContext.

Platform specifics (as far as I'm aware)

• .NET Core 1.1 (Runtime + SDK)
• EF Core 1.1
• Microsoft.EntityFrameworkCore.Tools 1.0.0-preview2-final
• Microsoft.EntityFrameworkCore.Design 1.0.0-preview2-final

解决方案

You are using a .NET Core 1.1 runtime but the old tooling packages (you should be using the latest tooling, as of this date it is preview4, which is still in alpha, contrary to the runtime - yeah, not very intuitive at first)

In summary, this is a Known Issue

• Update your project.json to use preview4 as stated in Announcing Entity Framework Core 1.1

"tools": {
    "Microsoft.EntityFrameworkCore.Tools.DotNet": "1.1.0-preview4"
}

• You may, or may not need to fix the SDK version by using a global.json just above the src folder which should contain your code as explained in Hanselman's blog

{
  "projects": [ "src", "test" ],
  "sdk": {
    "version": "1.0.0-preview2-1-003177"
  }
}

EDIT: Just to give you a more complete answer, this is how my project.json and my sample project looks like (all done in VS Code):

{
  "version": "1.0.0-*",
  "buildOptions": {
    "debugType": "portable",
    "emitEntryPoint": true
  },
  "dependencies": {
    "Microsoft.EntityFrameworkCore": "1.1.0-preview1-final",
    "Microsoft.EntityFrameworkCore.Design": "1.1.0-preview1-final",
    "Microsoft.EntityFrameworkCore.SqlServer": "1.1.0-preview1-final",
    "Microsoft.EntityFrameworkCore.SqlServer.Design": "1.1.0-preview1-final",
  },
  "frameworks": {
    "netcoreapp1.1": {
      "dependencies": {
        "Microsoft.NETCore.App": {
          "type": "platform",
          "version": "1.1.0"
        }
      },
      "imports": "dnxcore50"
    }
  },
  "tools": {
    "Microsoft.EntityFrameworkCore.Tools.DotNet": "1.1.0-preview4-final"
  }
}

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