Ошибка при сохранении сущностей не обеспечивающих доступ к свойствам внешнего ключа для их связей

(I’ve checked the related questions, and can’t find an answer.)

I’m doing some tests with Code First Entity Framework 6.
I have a «Child» entity that references two «Parent» entities.

I want to create the child entity and parent entities, and then save them all at once (so I can cut down on the number of db.Save() calls, and to keep it as one unit of work).

public class Child
{
    public int ChildID { get; set; }
    public string Name { get; set; }

    public virtual Parent Father { get; set; }
    public virtual Parent Mother { get; set; }
}

public class Parent
{
    public int ParentID { get; set; }
    public string Name { get; set; }

    [ForeignKey("Child")]
    public int? ChildID { get; set; }
    public virtual Child Child { get; set; }
}

(A bit of a confusing setup — the parents are actually the «children» of the child in the relationship. I know it’s bad abstraction. This is just a test.)

Controller:

    public ActionResult AddWithParents()
    {
        Parent father = new Parent { Name = "Test Father" };
        Parent mother = new Parent { Name = "Test Mother" };

        Child newChild = new Child
        {
            Name = "Test Child",
            Father = father,
            Mother = mother
        };


        db.Children.Add(newChild);

        father.Child = newChild;
        mother.Child = newChild;

        db.SaveChanges();            

        return RedirectToAction("Index");
    }

This works, but doesn’t populate the Parent.ChildID foreign key.

If I do something like father.Child = newChild, I get the following error:

An error occurred while saving entities that do not expose foreign key properties for their relationships. The EntityEntries property will return null because a single entity cannot be identified as the source of the exception. Handling of exceptions while saving can be made easier by exposing foreign key properties in your entity types. See the InnerException for details.
Unable to determine a valid ordering for dependent operations. Dependencies may exist due to foreign key constraints, model requirements, or store-generated values.

Is there any way to get this to work?

(I’ve checked the related questions, and can’t find an answer.)

I’m doing some tests with Code First Entity Framework 6.
I have a «Child» entity that references two «Parent» entities.

I want to create the child entity and parent entities, and then save them all at once (so I can cut down on the number of db.Save() calls, and to keep it as one unit of work).

public class Child
{
    public int ChildID { get; set; }
    public string Name { get; set; }

    public virtual Parent Father { get; set; }
    public virtual Parent Mother { get; set; }
}

public class Parent
{
    public int ParentID { get; set; }
    public string Name { get; set; }

    [ForeignKey("Child")]
    public int? ChildID { get; set; }
    public virtual Child Child { get; set; }
}

(A bit of a confusing setup — the parents are actually the «children» of the child in the relationship. I know it’s bad abstraction. This is just a test.)

Controller:

    public ActionResult AddWithParents()
    {
        Parent father = new Parent { Name = "Test Father" };
        Parent mother = new Parent { Name = "Test Mother" };

        Child newChild = new Child
        {
            Name = "Test Child",
            Father = father,
            Mother = mother
        };


        db.Children.Add(newChild);

        father.Child = newChild;
        mother.Child = newChild;

        db.SaveChanges();            

        return RedirectToAction("Index");
    }

This works, but doesn’t populate the Parent.ChildID foreign key.

If I do something like father.Child = newChild, I get the following error:

An error occurred while saving entities that do not expose foreign key properties for their relationships. The EntityEntries property will return null because a single entity cannot be identified as the source of the exception. Handling of exceptions while saving can be made easier by exposing foreign key properties in your entity types. See the InnerException for details.
Unable to determine a valid ordering for dependent operations. Dependencies may exist due to foreign key constraints, model requirements, or store-generated values.

Is there any way to get this to work?

We are using MVC in combination with Entity Framework.

At some point we are trying to establish a link between two entities.  This works fine in a unit-test, but gives the following error when tried from an MVC controller method:

“An error occurred while saving entities that do not expose foreign key properties for their relationships. The EntityEntries property will return null because a single entity cannot be identified as the source of the exception. Handling of exceptions while
saving can be made easier by exposing foreign key properties in your entity types. “

The (stripped down) classes:

public class Position : Entity
{
   public string Function { get; set; }
   public Organization Organization{ get; set; }
   // public Guid? OrganizationId { get; set; }
   // works when enabled!
}

public class Organization: Entity
{
   public string Name { get; set; } 
   public IList<Position> Contacts
   {
       get {return contacts;} 
       set { contacts = value; }
   }
 
   public class EntityConfiguration :
            EntityConfigurationBase<Organization>
   {
       public EntityConfiguration()
       {
           HasMany(p => p.Contacts)
               .WithOptional(y => y.Organization)
        }
   }
 
   private IList<Position> contacts = 
       new List<Position>();
}

The (stripped down) controller method that fails:

[HttpPost]
public ActionResult Edit(Position position, string organizationId = "")
{
    if (!ModelState.IsValid)
    {
        return View(position);
    }
    db.Entry(position).State = EntityState.Modified;
    if (!string.IsNullOrEmpty(organizationId))
    {
        Guid orgId = Guid.Parse(organizationId);
        Organization organization =
            db.Organizations
                .First(x => x.Id.Equals(orgId));
        position.Organization = organization;
    }
	db.SaveChanges();
    RedirectToAction("Index");
}

The unit test that passes:

[TestMethod]
public void LinkOrganizationToPositionTest()
{
    // arrange
    DbModel dbModel;
    Organization org;
    Position pos;
    Guid orgId;

    using (dbModel = new DbModel())
    {
        dbModel.Database.Delete();
        dbModel.Database.Create();

        // - first organization
        org = dbModel.Organizations.Create();
        org.Name = "TestOrgFirst";
        dbModel.Entry(org).State = EntityState.Added;

        pos = dbModel.Positions.Create();
        pos.Function = "TestFunc";
        dbModel.Entry(pos).State = EntityState.Added;

        // - link pos to first org
        pos.Organization = org;

        org = dbModel.Organizations.Create();
        org.Name = "TestOrgSecond";
        dbModel.Entry(org).State = EntityState.Added;
        orgId = org.Id;
        dbModel.SaveChanges();
    }

    // act
    // - obtain "fresh" model
    using (dbModel = new DbModel())
    {
        // - get second org
        org = dbModel.Organizations.Find(orgId);
        pos = dbModel.Positions.Find(pos.Id);
        pos.Organization = org;
        dbModel.SaveChanges();
    }

    // assert
    using (dbModel = new DbModel())
    {
        Position actual =
            dbModel.Positions
                .Include("Organization")
                    .First(x => x.Id.Equals(pos.Id));
        // - link was saved 
        Assert.AreEqual(
            "TestOrgSecond", 
            actual.Organization.Name
            );
    }
}

Why is the is the OrganizationId foreign key property required by the MVC?
 Is there a simple fix that doesn’t require  all the foreign-keys in the model?

We are using MVC in combination with Entity Framework.

At some point we are trying to establish a link between two entities.  This works fine in a unit-test, but gives the following error when tried from an MVC controller method:

“An error occurred while saving entities that do not expose foreign key properties for their relationships. The EntityEntries property will return null because a single entity cannot be identified as the source of the exception. Handling of exceptions while
saving can be made easier by exposing foreign key properties in your entity types. “

The (stripped down) classes:

public class Position : Entity
{
   public string Function { get; set; }
   public Organization Organization{ get; set; }
   // public Guid? OrganizationId { get; set; }
   // works when enabled!
}

public class Organization: Entity
{
   public string Name { get; set; } 
   public IList<Position> Contacts
   {
       get {return contacts;} 
       set { contacts = value; }
   }
 
   public class EntityConfiguration :
            EntityConfigurationBase<Organization>
   {
       public EntityConfiguration()
       {
           HasMany(p => p.Contacts)
               .WithOptional(y => y.Organization)
        }
   }
 
   private IList<Position> contacts = 
       new List<Position>();
}

The (stripped down) controller method that fails:

[HttpPost]
public ActionResult Edit(Position position, string organizationId = "")
{
    if (!ModelState.IsValid)
    {
        return View(position);
    }
    db.Entry(position).State = EntityState.Modified;
    if (!string.IsNullOrEmpty(organizationId))
    {
        Guid orgId = Guid.Parse(organizationId);
        Organization organization =
            db.Organizations
                .First(x => x.Id.Equals(orgId));
        position.Organization = organization;
    }
	db.SaveChanges();
    RedirectToAction("Index");
}

The unit test that passes:

[TestMethod]
public void LinkOrganizationToPositionTest()
{
    // arrange
    DbModel dbModel;
    Organization org;
    Position pos;
    Guid orgId;

    using (dbModel = new DbModel())
    {
        dbModel.Database.Delete();
        dbModel.Database.Create();

        // - first organization
        org = dbModel.Organizations.Create();
        org.Name = "TestOrgFirst";
        dbModel.Entry(org).State = EntityState.Added;

        pos = dbModel.Positions.Create();
        pos.Function = "TestFunc";
        dbModel.Entry(pos).State = EntityState.Added;

        // - link pos to first org
        pos.Organization = org;

        org = dbModel.Organizations.Create();
        org.Name = "TestOrgSecond";
        dbModel.Entry(org).State = EntityState.Added;
        orgId = org.Id;
        dbModel.SaveChanges();
    }

    // act
    // - obtain "fresh" model
    using (dbModel = new DbModel())
    {
        // - get second org
        org = dbModel.Organizations.Find(orgId);
        pos = dbModel.Positions.Find(pos.Id);
        pos.Organization = org;
        dbModel.SaveChanges();
    }

    // assert
    using (dbModel = new DbModel())
    {
        Position actual =
            dbModel.Positions
                .Include("Organization")
                    .First(x => x.Id.Equals(pos.Id));
        // - link was saved 
        Assert.AreEqual(
            "TestOrgSecond", 
            actual.Organization.Name
            );
    }
}

Why is the is the OrganizationId foreign key property required by the MVC?
 Is there a simple fix that doesn’t require  all the foreign-keys in the model?

public partial class ArtworkImage
{
    [Key]
    public int Id { get; set; }
    public string ImageURL { get; set; }
    public Artwork Artwork { get; set; }
}

public partial class Artwork
{
    [Key]
    public int Id { get; set; }
    public string Category { get; set; }
    public ICollection<ArtworkImage> ArtworkImage { get; set; }
}

public DbContext()
        : base("name=DbConnection")
    {
        this.Configuration.AutoDetectChangesEnabled = false;
    }

    public virtual DbSet<Artwork> Artworks { get; set; }

    public virtual DbSet<ArtworkImage> ArtworkImages { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Artwork>()
            .Property(e => e.Category)
            .IsFixedLength();

        Database.SetInitializer<DbContext>(null);
        base.OnModelCreating(modelBuilder);
    }

2 ответа

[Key]
public int Id { get; set; }

public partial class Artwork
{
    [Key]
    public int Id { get; set; }
    public string Category { get; set; }
    public ArtworkImage ArtworkImage { get; set; }
}

public partial class Artwork
{
    [Key]
    public int Id { get; set; }
    public string Category { get; set; }
    public IEnumerable<ArtworkImage> ArtworkImages { get; set; }
}

Для тех из вас, у кого все еще будет эта ошибка при правильном определении всех ключей, взгляните на свои объекты и убедитесь, что вы не оставляете поле datetime с нулевым значением.

Проблема была решена добавлением свойства FK.

garageEntity.Cars.Remove(carEntity);

context.Cars.Remove(carEntity);

Просто для тех, у кого могут быть похожие проблемы. У меня была такая же ошибка, но по другой причине. В одном из дочерних объектов я определил [Key] как значение, одинаковое для разных сохранений. Глупая ошибка с моей стороны, но сообщение об ошибке не сразу приводит вас к проблеме.

CreateTable(
    "dbo.LogEmailAddressStats",
    c => new
        {
            Id = c.Int(nullable: false, identity: true),
            EmailAddress = c.String(),
        })
    .PrimaryKey(t => t.Id);

CreateTable(
    "dbo.LogEmailAddressStatsFails",
    c => new
        {
            Id = c.Int(nullable: false), // EF missed to set identity: true!!
            Timestamp = c.DateTime(nullable: false),
        })
    .PrimaryKey(t => t.Id)
    .ForeignKey("dbo.LogEmailAddressStats", t => t.Id)
    .Index(t => t.Id);

update-database -target:{insert the name of the previous migration}

add-migration identity_fix

    public partial class identity_fix : DbMigration
    {
        public override void Up()
        {
            AlterColumn("dbo.LogEmailAddressStatsFails", "Id", c => c.Int(nullable: false, identity: true));
        }

        public override void Down()
        {
            AlterColumn("dbo.LogEmailAddressStatsFails", "Id", c => c.Int(nullable: false));
        }
    }

Эта проблема также может возникнуть из-за перевернутого объявления ключей. Если вы используете Fluent для настройки взаимосвязи, убедитесь, что левая и правая клавиши сопоставлены с правильным объектом.

public List<EdiSegment> EdiSegments { get; set; }

public virtual ICollection<EdiSegment> EdiSegments { get; set; }

У меня была такая же проблема. в моем случае это произошло из-за поля datetime с нулевым значением. Мне пришлось перенести значение на datetime, и все прошло нормально

PasmISOContext db = new PasmISOContext();
var user = new User();
user.CreationDate = DateTime.Now;
user.LastActivityDate = DateTime.Now;
user.LastLoginDate = DateTime.Now;
db.Users.Add(user);

db.SaveChanges();
user.Avatar = new Avatar() { Link = new Uri("http://myUrl/%2E%2E/%2E%2E") };
db.SaveChanges();


db.Users.Add(new User() { Avatar = new Avatar() { Link = new Uri("http://myUrl/%2E%2E/%2E%2E") } });
db.SaveChanges();

db.Users.Add(new User() { Avatar = new Avatar() { Link = new Uri("http://myUrl/%2E%2E/%2E%2E") } });
db.SaveChanges();

public class Avatar
{
    [Key]
    public int Id { get; set; }

    [Required]
    public string LinkInString { get; set; }

    [NotMapped]
    public Uri Link
    {
        get { return new Uri(LinkInString); }
        set { LinkInString = value.AbsoluteUri; }
    }
}

public class User
{
    [Key]
    public int Id { get; set; }
    public string UserName { get; set; }
    public string Email { get; set; }
    public string Password { get; set; }
    public Avatar Avatar { get; set; }
    public virtual ICollection<Question> Questions { get; set; }
    public virtual ICollection<Achievement> Achievements { get; set; }

    public DateTime CreationDate { get; set; }
    public DateTime LastLoginDate { get; set; }
    public DateTime LastActivityDate { get; set; }
}

задан abatishchev 13 January 2015 в 19:09

поделиться

Я объявляю некоторые сущности следующим образом:

Entity myEntity = new Entity();
myEntity.InnerProperties = new InnerProperties();
myEntity.OuterProperties = new OuterProperties();

Когда я отлаживаю код, идентификатор myEntity и идентификатор обоих свойств равен 0. Когда я запускаю эти строки:

_context.Entities.Add(myEntity);
_context.SaveChanges();

Я получаю это исключение: {«Произошла ошибка при сохранении объектов, которые не раскрывают свойства внешнего ключа для своих отношений. Свойство EntityEntries вернет значение null, поскольку один объект не может быть идентифицирован как источник исключения. Обработка исключений при сохранении может упростить, предоставив свойства внешнего ключа в ваших типах сущностей. Подробнее см. InnerException.»}

И я получаю это как внутреннее исключение:

Оператор обновления, вставки или удаления хранилища затронул непредвиденное количество строк (0). Объекты могли быть изменены или удалены после загрузки объектов. См. http://go.microsoft.com/fwlink/?LinkId=472540. для получения информации о понимании и обработке исключений оптимистического параллелизма.

Я получаю это исключение, потому что все идентификаторы равны нулю? Или я что-то еще упускаю?

Еще одна вещь: в Entity есть поле int, я его не заполняю. Это источник исключения?

Спасибо.