Enable-Migrations「未將對象引用設置爲對象的實例」

Question

我剛創建了一個新的服務結構服務，它將定期嘗試使用Entity Framework和Elastic Client Database庫將某些模型保存到SQL Azure。我試圖儘可能地對SQL Azure Elastic Sc​​ale Client Library EF示例（Elastic DB Tools EF Sample）進行建模。我處於需要啓用遷移的地步，但是當我運行Enable-Migrations時，我收到以下錯誤消息。我使用的是ContextTypeName參數，因爲它聽起來像是最終需要針對具有不同模型的相同數據庫的不同服務結構服務所需的。有什麼建議麼？

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

我已經通過指定Enable-Migrations命令-StartUpProjectName參數與數據庫方面，我國.NET框架DLL解決了同樣的異常問題。這個問題可能與奇怪的啓動項目 - 問題在.IsWebProject（）（asp.core在我的情況）。在Enable-Migrations Exception calling "SetData" with "2" argument(s)上查看更詳細的答案。