Enable-Migrations使用"2"参数调用"SetData"的异常

Question

我创建了一个基于.NET 4.6.2版本的库.
在库中,我添加了EntityFramework版本6.1.3包.
我创建了一个模型如下

using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace Components.Models
{
  public class Session
  {
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public string Id { get; set; }

    [Key]
    [Required]
    public string Identity { get; set; }

    [Required]
    public DateTime CreatedAt { get; set; }

    [Required]
    public DateTime UpdatedAt { get; set; }
  }
} 

和dbcontext

using System.Configuration;
using System.Data.Entity;
using System.Data.Entity.ModelConfiguration.Conventions;
using Components.Models;

namespace Components.DataContexts
{
  public class SessionContext : DbContext
  {
    public SessionContext() : base(ConfigurationManager.ConnectionStrings["sessiondb"].ConnectionString)
    {
    }

    public DbSet<Session> Sessions { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
      modelBuilder.Conventions.Remove<PluralizingEntitySetNameConvention>();
    }

  }
}

然后我尝试启用迁移并通过

PM> Enable-Migrations

声明,得到错误信息:

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:\C#\IndustryCloud\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.

我做错了什么？

更新 结构,如何构建projet

在sessiontest.cs中,我为db编写了测试.

[Test]
public void InsertARow_DbInitial_ExpectDbValue()
{

  var sn = new Session()
  {
    Identity = Random.Generate(15),
    CreatedAt = DateTime.Now,
    UpdatedAt = DateTime.Now
  };

  db.Sessions.Add(sn);
  db.SaveChanges();

}

在我编写单元测试的ComponentsTest项目中,app.config看起来如下:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <connectionStrings>
    <add connectionString="Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=Session;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=True;ApplicationIntent=ReadWrite;MultiSubnetFailover=False" name="sessiondb" />
  </connectionStrings>
</configuration>

在库(Component)本身app.config:

<?xml version="1.0" encoding="utf-8"?>
<configuration>

  <configSections>

    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 --></configSections>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="mssqllocaldb" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>

  <connectionStrings>
    <add connectionString="Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=Session;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=True;ApplicationIntent=ReadWrite;MultiSubnetFailover=False" name="sessiondb" />
  </connectionStrings>

</configuration>

Answer 1

其他答案表明这是您的启动项目的问题.

由于您的项目是库,您可以尝试根据此答案将单元测试项目设置为启动项目.

您还可以尝试根据此处接受的答案将Package Manager Console中的默认项目设置为库项目.

您可能会遇到创建迁移的问题.如果你需要进一步的控制,在EF6中你可以使用各种参数Enable-Migrations,详见答案,但我对这方面的知识不足以指导你.你可能需要做一些阅读.

Answer 2

2018更新 - 如果接受的答案没有帮助,请在EF6存储库中查看此github问题.显然,代码迁移命令不适用于新的项目格式.要使迁移命令起作用,您需要创建一个Class Library (.NET Framework)项目(旧标准),将所有文件移动到那里,添加所有必需的依赖项并运行命令.

编辑:我刚刚Class Library (.NET Standard)使用EntityFramework 6.2.0在VisualStudio 2017 15.6.6上创建了一个项目.如上所述创建"旧标准"项目可以解决这个问题.

Answer 3

要明确定义启动项目,可以使用以下命令:

Enable-Migrations -EnableAutomaticMigrations -ProjectName Components -StartupProjectName Components

参数是:

-项目名

指定将脚手架迁移配置类添加到的项目(configuration.cs).如果省略,则使用在包管理器控制台中选择的默认项目.

-StartUpProjectName

指定用于命名连接字符串的配置文件.如果省略,则使用指定项目的配置文件.

要获取该命令的更多详细信息,请运行:

get-help enable-migrations -Full