情况草图
我开发了一个系统,其中可以将许多材料(代码为Matetiaal)添加到广告中(在代码Zoeker中).这种关系很多很多.在这里你得到了我的课程结构.
+-------------------------------------+ many to many +-------------------------------+
| Zoeker | <--------------> | Materiaal |
+------------+------------------------+ +---------+---------------------+
| ID | int | | ID | int |
| Materialen | ICollection<Materiaal> | | Zoekers | ICollection<Zoeker> |
| Titel | string | | Naam | string |
+------------+------------------------+ +---------+---------------------+
我将使用下一个伪代码添加新材料和广告：
void Insert(Zoeker zoeker, string[] materialen)
{
foreach (string m in materialen)
{
Materiaal mat = materiaalRepo.GetByName(m);
if (mat == null)
{
mat = materiaalRepo.Insert(new Materiaal(m));
}
zoeker.Materialen.Add(mat);
}
zoekerRepo.Insert(zoeker);
}
换句话说,当必须添加新广告(Zoeker)时,我将检查数据库中是否已存在该材料.如果材料不存在,则materialenRepo.GetByName(string)方法返回null.如果是这样,请将新材质插入数据库并返回Materiaal对象.之后或者如果materialenRepo.GetByName(string)没有返回null,请将该材料添加到广告的Materialen属性并将其插入数据库.
要将数据库与我的应用程序连接,我使用Entity Framework.
我的问题
当我在下面的标题上使用代码时,我有这个例外：
System.InvalidOperationException: An entity object cannot be referenced by multiple instances ofIEntityChangeTracker.06002
当zoekerRepo.Insert(zoeker)时,在标记的行上抛出异常;叫做.
我的代码
在这里你可以找到我制作的代码.
服务
public class ZoekService
{
public int InsertZoeker(Zoeker zoeker, ApplicationUser user, string materialenString)
{
return InsertZoeker(zoeker, user, materialenString.Split(','));
}
public int InsertZoeker(Zoeker zoeker, ApplicationUser user, string[] materialen)
{
zoeker.Gebruiker = user;
zoeker.Materialen = new List<Materiaal>();
using (ApplicationDbContext ctx = new ApplicationDbContext())
{
ZoekerRepository zoekerRepo = new ZoekerRepository(ctx);
MateriaalRepository materiaalRepo = new MateriaalRepository(ctx);
// ^^^^ See update one
foreach (string m in materialen)
{
Materiaal materiaal = materiaalRepo.GetByNaam(m);
if (materiaal == null)
{
materiaal = materiaalRepo.Insert(new Materiaal(m));
// ^ See update three
}
zoeker.Materialen.Add(materiaal);
}
zoekerRepo.Insert(zoeker);
zoekerRepo.SaveChanges(); // <-- Pointer didn't come on this line.
return zoeker.ID;
}
}
}
库
ZoekerRepository扩展了GenericRepository< Zoeker>
public class ZoekerRepository : GenericRepository<Zoeker>
{
public ZoekerRepository()
{ }
public ZoekerRepository(ApplicationDbContext ctx): base(ctx)
{ }
// Some other methods I've add or will override.
}
MateriaalRepository扩展了GenericRepository< Materiaal>
public class MateriaalRepository : GenericRepository<Materiaal>
{
public MateriaalRepository()
{ }
public MateriaalRepository(ApplicationDbContext ctx): base(ctx)
{ }
public Materiaal GetByNaam(string naam)
{
return (from m in dbSet
where m.Naam.Equals(naam)
select m).SingleOrDefault<Materiaal>();
}
// Some other methods I've add or will override.
}
GenericRepository< TEntity>
public class GenericRepo<TEntity> where TEntity : class
{
internal ApplicationDbContext context;
internal DbSet<TEntity> dbSet;
public GenericRepo()
{
context = new ApplicationDbContext();
dbSet = context.Set<TEntity>();
}
public GenericRepo(ApplicationDbContext context)
{
this.context = context;
this.dbSet = context.Set<TEntity>();
}
public virtual TEntity Insert(TEntity entity)
{
return dbSet.Add(entity); // <-- after `zoekerRepo.Insert(Zoeker)` the exception
// will be thrown on this line.
}
public void SaveChanges()
{
try
{
context.SaveChanges();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}
}
我做了什么
当然我已经尝试了其他代码,但所有代码都给出了相同的异常.我将创建我的代码,以便材料的存储库使用名为GenericRepo< TEntity>的相同通用类与广告存储库中的存储库分隔. (除了我要添加或覆盖的东西).我将尽可能多地重用它.一次用于GenericRepo< Zoeker>和GenericRepo< Materiaal>的另一个时间.
我的问题
我怎么能解决这个bug？
更新一个
这个问题与entity object cannot be referenced by multiple instances of IEntityChangeTracker. while adding related objects to entity in Entity Framework 4.1不重复,因为我使用相同的上下文,如接受的答案说：
You can fix this by creating a context outside of the service classes and injecting and using it in both services:
06007
请参阅上面代码的评论.
更新两个
在这里,我已经完成了我的代码的新部分.
控制器
public class DeelController : Controller
{
private UserManager<ApplicationUser> UserManager { get; set; }
private ZoekService _zoekservice = new ZoekService();
public DeelController()
{
this.UserManager = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(ApplicationDbContext));
}
[HttpGet]
[Authorize]
public ActionResult Nieuw()
{
return View(new Zoeker());
}
[HttpPost]
[Authorize]
[ValidateAntiForgeryToken]
public async Task<ActionResult> Nieuw(Zoeker zoeker)
{
_zoekservice.InsertZoeker(zoeker, await UserManager.FindByNameAsync(User.Identity.Name), zoeker.MaterialenString);
return RedirectToAction(nameof(Index));
}
}
类
Zoeker扩展了Post
public class Zoeker: Post
{
public virtual ICollection<Materiaal> Materialen { get; set; }
public virtual ICollection<ApplicationUser> Delers { get; set; }
[NotMapped]
public string MaterialenString { get; set; } // <-- contains a comma separated
// list of all materials
}
岗位
public class Post
{
[Key]
public int ID { get; set; }
public string Titel { get; set; }
public string Omschrijving { get; set; }
public virtual ApplicationUser Gebruiker { get; set; }
public string GebruikerID { get; set; }
public DateTime StartPeriode { get; set; }
public DateTime? Verwijderd { get; private set; }
public DateTime? Opgelost { get; private set; }
public DateTime? Belangerijk { get; private set; }
public virtual ICollection<Antwoord> Antwoorden { get; set; }
}
更新三
我也尝试使用此代码替换上面代码中的注释行,但没有解决此错误：
materiaal = /*materiaalRepo.Insert(*/ new Materiaal(m); //);
如果我使用不存在的材料,使用更新三的代码,我再次遇到了这个错误.
更新四
如果我使用观察者,我会看到：
Material [0]得到了一个字段_entityWrapper类型的EntityWrapperWithoutRelationships< System.Data.Entity.DynamicProxies.Materiaal_E0DDEFDA63D33C75C64324662B40FDC414EC19CA4AD6BF18443B63FC60015374>.注意：此材料已存在于数据库中.在这里我也有同样的错误.
更新五
我也取代了`InsertZoeker(Zoeker
public int InsertZoeker(Zoeker zoeker, ApplicationUser user, string[] materialen)
{
Zoeker newZoeker = new Zoeker()
{
Gebruiker = user,
StartPeriode = DateTime.Now,
Materialen = new List<Materiaal>(),
Titel = zoeker.Titel,
Omschrijving = zoeker.Omschrijving
};
using (ApplicationDbContext ctx = new ApplicationDbContext())
{
ZoekerRepository zoekerRepo = new ZoekerRepository(ctx);
MateriaalRepository materiaalRepo = new MateriaalRepository(ctx);
foreach (string m in materialen)
{
Materiaal materiaal = materiaalRepo.GetMateriaalByNaam(m);
if (materiaal == null)
{
materiaal = /*materiaalRepo.Insert(*/ new Materiaal(m); //);
}
newZoeker.Materialen.Add(materiaal);
}
zoekerRepo.Insert(newZoeker);
zoekerRepo.SaveChanges();
return zoeker.ID;
}
}
最佳答案 愚蠢的我,我正在使用其他上下文让我的DeelController内的用户.我在我的问题中删除了该代码.
@mwwills：这确实是一个重复的问题.
@everyone_else：对不起,我已经做到了.
