Question

我知道Visual Studio 2013明天正式推出，希望会有更多随附的文档，特别是它关于ASP.NET身份。我在跳的同时有人可以帮助我。

我所要做的就是将当前登录用户的UserID作为外键输入到名为Retailer的表中。

首先是我得到的错误消息

IEntityChangeTracker的多个实例无法引用实体对象。

这是我的POCO：

public class Retailer
{
    [Key]
    public int RetailerId { get; set; }
    public string BusinessName { get; set; }
    public string PhoneNumber { get; set; }
    public string ManagerName { get; set; }
    public Enums.Industry Industry { get; set; }
    public virtual ApplicationUser UserProfile { get; set; }

}

以下是Entity Framework CodeFirst如何从上面的类创建表：

CreateTable(
    "dbo.Retailers",
    c => new
        {
            RetailerId = c.Int(nullable: false, identity: true),
            BusinessName = c.String(),
            PhoneNumber = c.String(),
            ManagerName = c.String(),
            Industry = c.Int(nullable: false),
            UserProfile_Id = c.String(maxLength: 128),
        })
    .PrimaryKey(t => t.RetailerId)
    .ForeignKey("dbo.AspNetUsers", t => t.UserProfile_Id)
    .Index(t => t.UserProfile_Id);

以下是我在控制器中将记录保存到此表的地方：

if (ModelState.IsValid)
{
    var currentUser = await UserManager.FindByIdAsync(User.Identity.GetUserId());
    retailer.UserProfile = currentUser;
    db.Retailers.Add(retailer);
    await db.SaveChangesAsync();
    return RedirectToAction("Index");
}

对于完全披露，这里有一些堆栈跟踪：

InvalidOperationException: An entity object cannot be referenced by multiple instances of IEntityChangeTracker.]
   System.Data.Entity.Core.Objects.ObjectContext.VerifyContextForAddOrAttach(IEntityWrapper wrappedEntity) +189
   System.Data.Entity.Core.Objects.ObjectContext.AddSingleObject(EntitySet entitySet, IEntityWrapper wrappedEntity, String argumentName) +126
   System.Data.Entity.Core.Objects.DataClasses.RelatedEnd.AddEntityToObjectStateManager(IEntityWrapper wrappedEntity, Boolean doAttach) +98
   System.Data.Entity.Core.Objects.DataClasses.EntityReference.AddEntityToObjectStateManager(IEntityWrapper wrappedEntity, Boolean doAttach) +65
   System.Data.Entity.Core.Objects.DataClasses.RelatedEnd.AddGraphToObjectStateManager(IEntityWrapper wrappedEntity, Boolean relationshipAlreadyExists, Boolean addRelationshipAsUnchanged, Boolean doAttach) +67
   System.Data.Entity.Core.Objects.DataClasses.RelatedEnd.IncludeEntity(IEntityWrapper wrappedEntity, Boolean addRelationshipAsUnchanged, Boolean doAttach) +341
   System.Data.Entity.Core.Objects.DataClasses.EntityReference`1.Include(Boolean addRelationshipAsUnchanged, Boolean doAttach) +210
   System.Data.Entity.Core.Objects.DataClasses.RelationshipManager.AddRelatedEntitiesToObjectStateManager(Boolean doAttach) +164
   System.Data.Entity.Core.Objects.ObjectContext.AddObject(String entitySetName, Object entity) +520
   System.Data.Entity.Internal.Linq.<>c__DisplayClassd.<Add>b__c() +97
   System.Data.Entity.Internal.Linq.InternalSet`1.ActOnSet(Action action, EntityState newState, Object entity, String methodName) +355
   System.Data.Entity.Internal.Linq.InternalSet`1.Add(Object entity) +200
   System.Data.Entity.DbSet`1.Add(TEntity entity) +130
   ValueCardPremium.Web.Controllers.<Create>d__7.MoveNext() in c:\Users\Valentine\Documents\Visual Studio 2013\Projects\ValueCardProjectPremium\ValueCardPremium.Web\Controllers\RetailerController.cs:70
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +93
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52
   System.Runtime.CompilerServices.TaskAwaiter.GetResult() +21
   lambda_method(Closure , Task ) +64

Answer 1

UserManager使用它自己的DbContext从数据库加载数据。您将需要从用于添加引用的相同dbContext中检索用户。类似的东西：

var currentUMUser = await UserManager.FindByIdAsync(User.Identity.GetUserId());
var currentUser = db.Users.Find(currentUMUser.UserID);
retailer.UserProfile = currentUser;
db.Retailers.Add(retailer);
await db.SaveChangesAsync();
return RedirectToAction("Index");

当然，您必须使用实际适用于您的模型和DbContext的任何方法从您的数据库中检索用户。

Answer 2

添加using声明：

using Microsoft.AspNet.Identity;

然后您可以使用以下命令检索UserId：

var a = User.Identity.GetUserId();

ASP.NET MVC 5身份应用程序用户作为外键

2 个答案: