EF Core Scaffold DbContext

Posted 2021-05-03

我有脚手架DbContext的问题。我正在使用最新的.NET Core 1.1.0 SDK，我正在遵循这个指南：https://docs.microsoft.com/en-us/ef/core/get-started/aspnetcore/existing-db

但是当我在软件包管理器控制台中运行以下命令时：Scaffold-DbContext "<connection-string>" Microsoft.EntityFrameworkCore.SqlServer -OutputDir Models我得到了异常。

project.json

  "dependencies": {
    "Microsoft.EntityFrameworkCore": "1.1.0",
    "Microsoft.EntityFrameworkCore.Design": "1.1.0",
    "Microsoft.EntityFrameworkCore.SqlServer": "1.1.0",
    "Microsoft.EntityFrameworkCore.SqlServer.Design": "1.1.0",
    "Microsoft.EntityFrameworkCore.Tools": "1.1.0-preview4-final",
    "NETStandard.Library": "1.6.1"
  },

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

  "frameworks": {
    "netstandard1.6": {
      "imports": [
        "dnxcore50"
      ]
    }
  }

例外

System.IO.FileNotFoundException: Could not load file or assembly 
'System.Data.SqlClient, Version=4.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.
File name: 'System.Data.SqlClient, Version=4.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.SqlServerDatabaseModelFactory.Create(String connectionString, TableSelectionSet tableSelectionSet)
   at Microsoft.EntityFrameworkCore.Scaffolding.RelationalScaffoldingModelFactory.Create(String connectionString, TableSelectionSet tableSelectionSet)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.SqlServerScaffoldingModelFactory.Create(String connectionString, TableSelectionSet tableSelectionSet)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.ReverseEngineeringGenerator.GetMetadataModel(ReverseEngineeringConfiguration configuration)
   at Microsoft.EntityFrameworkCore.Scaffolding.Internal.ReverseEngineeringGenerator.GenerateAsync(ReverseEngineeringConfiguration configuration, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Design.Internal.DatabaseOperations.ScaffoldContextAsync(String provider, String connectionString, String outputDir, String dbContextClassName, IEnumerable`1 schemas, IEnumerable`1 tables, Boolean useDataAnnotations, Boolean overwriteFiles, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.<ScaffoldContextImpl>d__22.MoveNext()
   at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source, Int32& length)
   at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass4_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Could not load file or assembly 'System.Data.SqlClient, Version=4.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.

答案

目前的解决方法是在可执行项目中执行脚手架，该项目在解决方案中配置为启动项目。