dotnet ef add migrations返回null connect striing

Question

我正在使用新的“dotnet”CLI来完成我的初始EF 7.0迁移。我的连接字符串如下：

"Data Source=RICHSOLUTIONS\\SSDEV2014;Initial Catalog=TheWorldDB;Integrated Security=True"

但是，当我进入Developer Command提示符并输入

时

dotnet ef migrations add MyFirstMigration

我收到以下错误：

Project TheWorld (.NETCoreApp,Version=v1.0) was previously compiled. Skipping compilation.
System.ArgumentNullException: Value cannot be null.
Parameter name: connectionString
   at Microsoft.EntityFrameworkCore.Utilities.Check.NotEmpty(String value, String parameterName).....

project.json是

 "dependencies": {
    "EntityFramework.Commands": "7.0.0-rc1-final",
    "EntityFramework.SqlServer": "7.0.0-beta8",
    "Microsoft.AspNetCore.Hosting.Abstractions": "1.0.0-rc2-final",
    "Microsoft.AspNetCore.Mvc": "1.0.0-rc2-final",
    "Microsoft.AspNetCore.Mvc.TagHelpers": "1.0.0-rc2-final",
    "Microsoft.AspNetCore.Razor.Tools": "1.0.0-preview1-final",
    "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0-rc2-final",
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": "1.0.0-preview1-final",
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.0-rc2-final",
    "Microsoft.AspNetCore.StaticFiles": "1.0.0-rc2-final",
    "Microsoft.EntityFrameworkCore": "1.0.0-rc2-final",
    "Microsoft.EntityFrameworkCore.SqlServer": "1.0.0-rc2-final",
    "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview1-final",
    "Microsoft.Extensions.Configuration.EnvironmentVariables": "1.0.0-rc2-final",
    "Microsoft.Extensions.Configuration.FileExtensions": "1.0.0-rc2-final",
    "Microsoft.Extensions.Configuration.Json": "1.0.0-rc2-final",
    "Microsoft.Extensions.SecretManager.Tools": "1.0.0-preview1-final",
    "Microsoft.Framework.Runtime.Abstractions": "1.0.0-beta5",
    "Microsoft.NETCore.App": {
      "version": "1.0.0-rc2-3002702",
      "type": "platform"
    },
    "Microsoft.VisualStudio.Web.CodeGeneration.Tools": "1.0.0-preview1-final"
  },

  "tools": {
    "Microsoft.AspNetCore.Razor.Tools": {
      "version": "1.0.0-preview1-final",
      "imports": "portable-net45+win8+dnxcore50"
    },
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": {
      "version": "1.0.0-preview1-final",
      "imports": "portable-net45+win8+dnxcore50"
    },
    "Microsoft.EntityFrameworkCore.Tools": {
      "version": "1.0.0-preview1-final",
      "imports": [
        "portable-net45+win8+dnxcore50",
        "portable-net45+win8"
      ]
    },
    "Microsoft.Extensions.SecretManager.Tools": {
      "version": "1.0.0-preview1-final",
      "imports": "portable-net45+win8+dnxcore50"
    },
    "Microsoft.VisualStudio.Web.CodeGeneration.Tools": {
      "version": "1.0.0-preview1-final",
      "imports": [
        "portable-net45+win8+dnxcore50",
        "portable-net45+win8"
      ]
    }
  },


  "frameworks": {
    "netcoreapp1.0": {
      "imports": [
        "dotnet5.6",
        "dnxcore50",
        "portable-net45+win8"
      ]
    }
  },

  "buildOptions": {
    "emitEntryPoint": true,
    "preserveCompilationContext": true
  },


  "runtimeOptions": {
    "gcServer": true
  },

  "publishOptions": {
    "include": [
      "wwwroot",
      "web.config"
    ]
  },

  "scripts": {
    "postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ]
  },
  "userSecretsId": "aspnet-TheWorld-20160624024822"
}