启用 - 迁移"对象引用未设置为对象的实例"

Question

我刚刚创建了一个新的服务结构服务,它将使用Entity Framework和Elastic Client Database库定期尝试将一些模型保存到SQL Azure.我正在尝试尽可能地对SQL Azure Elastic Sc​​ale Client Library EF示例(Elastic DB Tools EF Sample)进行建模.我正处于需要启用迁移的位置,但是当我运行Enable-Migrations时,我收到以下错误消息.我正在使用ContextTypeName参数,因为如果我最终将针对具有不同模型的相同数据库使用不同的服务结构服务,它听起来就像是需要的.有什么建议？

PM> Enable-Migrations -ContextTypeName "ServiceHealth.DbService"
Exception calling "SetData" with "2" argument(s): "Type 'Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.Automation.OAProject' in assembly 'Microsoft.VisualStudio.ProjectSystem.VS.Implementation, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' is 
not marked as serializable."
At C:\eNowCloud\eNow.MicroServices\packages\EntityFramework.6.1.3\tools\EntityFramework.psm1:720 char:5
+     $domain.SetData('startUpProject', $startUpProject)
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : SerializationException

System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Data.Entity.Migrations.Extensions.ProjectExtensions.GetProjectTypes(Project project, Int32 shellVersion)
   at System.Data.Entity.Migrations.Extensions.ProjectExtensions.IsWebProject(Project project)
   at System.Data.Entity.Migrations.MigrationsDomainCommand.GetFacade(String configurationTypeName, Boolean useContextWorkingDirectory)
   at System.Data.Entity.Migrations.EnableMigrationsCommand.FindContextToEnable(String contextTypeName)
   at System.Data.Entity.Migrations.EnableMigrationsCommand.<>c__DisplayClass2.<.ctor>b__0()
   at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)
Object reference not set to an instance of an object.

Answer 1

通过使用db上下文向.NET Framework dll 指定命令-StartUpProjectName参数，我已经解决了相同的异常问题Enable-Migrations。问题可能出在奇怪的启动项目上-.IsWebProject（）中的问题（在我的情况下为asp.core）。请参阅有关Enable-Migrations异常，并使用“ 2”个参数调用“ SetData”的详细解答。