带有 dnx 项目的 EF 6-C#/.NET问题

EF 6 with a dnx project(带有 dnx 项目的 EF 6)

本文介绍了带有 dnx 项目的 EF 6的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

I have a new ASP.net 5 dnx class library I am using for entity framework. I need to target EF 6 because some features I need are not in EF 7.

First the EF tools (like enable-migration) were not there. I added an old style class library and installed EF 6 and now the commands are there.

When I run enable migrations I get this error:

PM> Enable-Migrations

Exception calling "SetData" with "2" argument(s): "Type 'Microsoft.VisualStudio.ProjectSystem.VS.Implementation.Package.Automation.OAProject' in assembly 'Microsoft.VisualStudio.ProjectSystem.VS.Implementation, Version=14.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' is not marked as serializable." At D:ProjectsRebusFMSCodeCurrentFMSSupportFMSSupportpackagesEntityFramework.6.1.3 oolsEntityFramework.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.

I have tried different options for enable-migration such as specifying a startup project or the contextTypeName.

Any ideas?

解决方案

Following this recommendation, EF6 data projects should use the existing .NET Framework class library csproj type.

Even after following the recommendations, I was still getting the same error. Unloading your ASP.NET Core project(s) and then invoking the Enable-Migrations command on the appropriate csproj should allow the command to execute. You can unload a project by right-clicking on the .NET Core project and choosing the 'Unload Project' option. It should also be noted that the Package Manager Console window has a 'Default project:' drop-down selection. You should choose the project with your DbContext.

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