我知道Visual Studio 2013明天正式推出,希望会有更多的随附文档,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作为外键访问我称为Retailer的表.
首先是我得到的错误消息
An entity object cannot be referenced by multiple instances of IEntityChangeTracker.
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);
这是我试图在我的控制器中将记录保存到此表的位置：
if (ModelState.IsValid)
{
var currentUser = await UserManager.FindByIdAsync(User.Identity.GetUserId());
retailer.UserProfile = currentUser;
db.Retailers.Add(retailer);
await db.SaveChangesAsync();
return RedirectToAction("Index");
}
并且为了完全公开,这里是一些堆栈跟踪：
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 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
解决方法
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.就像是：
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");
