在EF数据访问层，一个实体对象不能被多个IEntityChangeTracker实例引用
本文关键字：不能 对象 实体 引用 实例 IEntityChangeTracker 一个 访问 数据 EF | 更新日期: 2023-09-27 18:09:11
我已经看到了很多关于相同主题的问题，但到目前为止还没有找到解决方案。给我带来问题的代码是:
public async Task<IHttpActionResult> Post(FullOrderViewModel fullOrder)
{
//Get all order items
List<OrderItem> orderItems = new List<OrderItem>();
foreach (var oi in fullOrder.Order)
{
var color = _colorRepo.Find(oi.ColorId);
var item = new OrderItem
{
Quantity = oi.Quantity,
Color = color
};
orderItems.Add(item);
}
//Get customer id
var customer = await _adminRepo.GetCustomerByUserName(fullOrder.Customer.UserName);
var billAddress = _addressRepo.All.FirstOrDefault(x => x.AddressLine == fullOrder.BillingAddress.AddressLine && x.PostalCode == fullOrder.BillingAddress.PostalCode);
var deliveryAddress = _addressRepo.All.FirstOrDefault(x => x.AddressLine == fullOrder.DeliveryAddress.AddressLine && x.PostalCode == fullOrder.DeliveryAddress.PostalCode);
//CASE : sample order
if (fullOrder.OrderType == OrderType.Sample)
{
var order = new SampleOrder {
Type = OrderType.Sample,
Status = "Unauthorized",
Origin = Origin.Online,
OrderItems = orderItems,
CreationDate = DateTime.Now,
CustomerId = customer.Id,
BillAddressId = billAddress.AddressId,
DeliveryAddressId = deliveryAddress.AddressId
};
try
{
_sampleOrderRepo.InserGraph(order);
_unitOfWork.Save();
}
catch (Exception e)
{
return InternalServerError(e);
}
我获得存储库的方式是通过OrderController构造函数中的依赖注入，所以我相信这是一种标准方式。我的每个repos都是这样构建的:
public class SampleOrderRepository : EntityRepository<SampleOrder, IPhoeniceUnitOfWork<PhoeniceContext>>, ISampleOrderRepository
{
public SampleOrderRepository(IPhoeniceUnitOfWork<PhoeniceContext> unitOfWork) : base(unitOfWork)
{
}
protected override IDbSet<SampleOrder> List(IPhoeniceUnitOfWork<PhoeniceContext> unitOfWork)
{
return unitOfWork.Context.SampleOrders;
}
protected override Expression<Func<SampleOrder, bool>> FindInt(int id)
{
return x => x.OrderId == id;
}
}
重写通用实体存储库中的方法:
public abstract class EntityRepository<T, TContext> : IEntityRepository<T>
where T : class, IObjectWithState
where TContext : IUnitOfWork<EntityContext>
{
protected readonly TContext _unitOfWork;
protected EntityRepository(TContext unitOfWork)
{
_unitOfWork = unitOfWork;
}
protected virtual IDbSet<T> List(TContext unitOfWork)
{
throw new NotImplementedException("List operation not implemented!");
}
protected virtual Expression<Func<T, bool>> FindInt(int id)
{
throw new NotImplementedException("Finding entity with an int is not implemented!");
}
protected virtual Expression<Func<T, bool>> FindString(string id)
{
throw new NotImplementedException("Finding entity with an int is not implemented!");
}
public virtual IQueryable<T> All { get { return List(_unitOfWork); } }
public virtual IQueryable<T> AllIncluding(params Expression<Func<T, object>>[] includeProperties)
{
return includeProperties.Aggregate(All, (current, includeProperty) => current.Include(includeProperty));
}
public virtual T Find(int id)
{
return All.FirstOrDefault(FindInt(id));
}
public virtual T FindByString(string id)
{
return All.FirstOrDefault(FindString(id));
}
public virtual void InserGraph(T entity)
{
List(_unitOfWork).Add(entity);
}
public void InsertOrUpdate(T entity)
{
if (entity.ObjectState == State.Added) // New entity
{
_unitOfWork.Context.Entry(entity).State = EntityState.Added;
}
else // Existing entity
{
_unitOfWork.Context.Entry(entity).State = EntityState.Modified;
_unitOfWork.Context.ApplyStateChanges();
}
}
public virtual void Delete(int id)
{
var entity = Find(id);
List(_unitOfWork).Remove(entity);
}
public void Dispose()
{
}
}
最后这是我的UnitOfWork项目:
public class PhoeniceUnitOfWork : IPhoeniceUnitOfWork<PhoeniceContext>
{
private readonly PhoeniceContext _context;
public PhoeniceUnitOfWork() : base()
{
_context = new PhoeniceContext();
}
//Left for testing purposes
public PhoeniceUnitOfWork(PhoeniceContext context)
{
_context = context;
}
public int Save()
{
return _context.SaveChanges();
}
public void Dispose()
{
_context.Dispose();
}
public IAddressRepository AddressRepository
{
get { return new AddressRepository(this); }
}
public IColorRepository ColorRepository
{
get { return new ColorRepository(this); }
}
public IHideOrderRepository HideOrderReposiotory
{
get { return new HideOrderRepository(this); }
}
public ISampleOrderRepository SampleOrderRepository
{
get { return new SampleOrderRepository(this); }
}
public ITaxonomyRepository TaxonomyRepository
{
get { return new TaxonomyRepository(this); }
}
PhoeniceContext IUnitOfWork<PhoeniceContext>.Context
{
get { return _context; }
}
}
和我使用的上下文
public class PhoeniceContext : EntityContext
{
// You can add custom code to this file. Changes will not be overwritten.
//
// If you want Entity Framework to drop and regenerate your database
// automatically whenever you change your model schema, add the following
// code to the Application_Start method in your Global.asax file.
// Note: this will destroy and re-create your database with every model change.
//
// System.Data.Entity.Database.SetInitializer(new System.Data.Entity.DropCreateDatabaseIfModelChanges<Phoenice.EntityFramework.Models.PhoeniceContext>());
public PhoeniceContext()
: base("Phoenice")
{
Database.SetInitializer<PhoeniceContext>(new DropCreateIfChangeInitializer());
//Database.SetInitializer<PhoeniceContext>(new DropCreateDatabaseAlways());
}
public DbSet<Address> Addresses { get; set; }
public DbSet<SampleOrder> SampleOrders { get; set; }
public DbSet<HideOrder> HideOrders { get; set; }
public DbSet<OrderItem> OrderItems { get; set; }
public DbSet<Color> Colors { get; set; }
public DbSet<Taxonomy> Taxonomies { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
//There is OnModelCreating already overwritten in IdentityDbContext
//with all details required for ASP.NET identity
base.OnModelCreating(modelBuilder);
//solution for this mapping: http://stackoverflow.com/questions/11632951/primary-key-violation-inheritance-using-ef-code-first
modelBuilder.Entity<SampleOrder>()
.HasKey(x => x.OrderId)
.Map(m =>
{
//Requires EF 6.1
m.MapInheritedProperties();
m.ToTable("SampleOrders");
})
.Property(x => x.OrderId)
.HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
modelBuilder.Entity<HideOrder>().Map(m =>
{
//Requires EF 6.1
m.MapInheritedProperties();
m.ToTable("HideOrders");
});
modelBuilder.Entity<HideOrder>().HasKey(x => x.OrderId);
}
}
我知道我展示了很多代码，但希望这些都是数据访问层的构建块。出于某种原因，当我在SampleOrders上调用InsertGraph方法时，我得到"一个实体对象不能被IEntityChangeTracker的多个实例引用"异常。我把这段代码看了几十遍，还是不明白为什么会抛出这个错误消息
我不确定我的答案，但我建议你如下:
我的版本的实体框架是有点不同，所以我不确定你会有所有需要的功能。当你这样做
List<OrderItem> orderItems = new List<OrderItem>();
foreach (var oi in fullOrder.Order)
{
var color = _colorRepo.Find(oi.ColorId);
var item = new OrderItem
{
Quantity = oi.Quantity,
Color = color
};
orderItems.Add(item);
}
我认为你应该首先分离所有的oi对象然后代码应该像
这样List<OrderItem> orderItems = new List<OrderItem>();
foreach (var oi in fullOrder.Order)
{
//detach oi
//attach oi
var color = _colorRepo.Find(oi.ColorId);
var item = new OrderItem
{
Quantity = oi.Quantity,
Color = color
};
orderItems.Add(item);
}
orderItems中的项包含color。返回值:
_colorRepo.Find(oi.ColorId);
colorRepo保存了color的实体。
下一行的顺序由另一个repo使用，但在'order'中有来自前一个repo的颜色。
_sampleOrderRepo.InserGraph(order);
两个repo持有相同的实体对象，从而导致此异常。
要避免这个问题，你可以做两件事:
每次使用_colorRepo.Find():
创建一个新的Color对象var color = new Color()
{
id = oi.ColorId
}
或通过将功能移动到服务