EntityReference的EntityKey属性值不匹配？

Question

我正在尝试添加我创建的一些实体。当我尝试将有问题的实体添加到集合中时(参见下面的代码)，我得到以下错误：

“无法添加或附加对象，因为其EntityReference的EntityKey属性值与此对象的EntityKey不匹配。”

不过，我不知道它指的是什么entitykey。下面是代码，可能还有一种更好的方法来实现这一点：

public Internship CreateInternship(Internship internshipToCreate)
{
    try
    {
        Contact contactToCreate = new Contact();

        contactToCreate.Fax = internshipToCreate.contacts.Fax;
        contactToCreate.Extension = internshipToCreate.contacts.Extension;
        contactToCreate.FirstName = internshipToCreate.contacts.FirstName;
        contactToCreate.MiddleName = internshipToCreate.contacts.MiddleName;
        contactToCreate.LastName = internshipToCreate.contacts.LastName;
        contactToCreate.PhoneNumber = internshipToCreate.contacts.PhoneNumber;
        contactToCreate.StreetAddress = internshipToCreate.contacts.StreetAddress;
        contactToCreate.PostalCode = internshipToCreate.contacts.PostalCode;
        contactToCreate.ContactEmail = internshipToCreate.contacts.ContactEmail;

        contactToCreate.statesReference.EntityKey =
                    new EntityKey("InternshipEntities.StateSet", "ID", internshipToCreate.contacts.states.ID);
        contactToCreate.countriesReference.EntityKey =
                    new EntityKey("InternshipEntities.CountrySet", "ID", internshipToCreate.contacts.countries.ID);

        _internshipEntities.AddToContactSet(contactToCreate);
        _internshipEntities.SaveChanges();

        try
        {
            Availability availabilityToCreate = new Availability();

            availabilityToCreate.StartDate = internshipToCreate.availability.StartDate;
            availabilityToCreate.EndDate = internshipToCreate.availability.EndDate;
            availabilityToCreate.Negotiable = internshipToCreate.availability.Negotiable;

            _internshipEntities.AddToAvailabilitySet(availabilityToCreate);
            _internshipEntities.SaveChanges();

            try
            {
                internshipToCreate.contactsReference.EntityKey =
                    new EntityKey("InternshipEntities.ContactSet", "ID", contactToCreate.ID);
                internshipToCreate.availabilityReference.EntityKey =
                    new EntityKey("InternshipEntities.AvailabilitySet", "ID", availabilityToCreate.ID);
                internshipToCreate.classificationsReference.EntityKey =
                    new EntityKey("InternshipEntities.ClassificationSet", "ID", internshipToCreate.classifications.ID);
                internshipToCreate.educationReference.EntityKey =
                    new EntityKey("InternshipEntities.EducationSet", "ID", internshipToCreate.education.ID);

                _internshipEntities.AddToInternshipSet(internshipToCreate); //exception here
                _internshipEntities.SaveChanges();

                return internshipToCreate;
            }
            catch(Exception e)
            {
                throw e; 
            }
        }
        catch(Exception e)
        {
            throw e;
        }
    }
    catch(Exception e)
    {
        throw e;
    }

}

当我跟踪时，除了错误之外没有给出其他信息，所以我甚至不确定哪个键是问题所在。

编辑:这是最终工作的版本：

using (TransactionScope scope = new TransactionScope())
{
    try
    {
        Contact contactToCreate = new Contact();
        Availability availabilityToCreate = new Availability();
        Internship i = new Internship();

        // Set the contact entity values;

        contactToCreate.Fax = internshipToCreate.contacts.Fax;
        //...
        //ommited for brevity
        //...
        contactToCreate.ContactEmail = internshipToCreate.contacts.ContactEmail;

        // Set the contact entity references to existing tables

        contactToCreate.statesReference.EntityKey =
                    new EntityKey("InternshipEntities.StateSet", "ID", internshipToCreate.contacts.states.ID);
        contactToCreate.countriesReference.EntityKey =
                    new EntityKey("InternshipEntities.CountrySet", "ID", internshipToCreate.contacts.countries.ID);

        // Add contact

        _internshipEntities.AddToContactSet(contactToCreate);

        // Set the availability entity values;

        availabilityToCreate.StartDate = internshipToCreate.availability.StartDate;
        availabilityToCreate.EndDate = internshipToCreate.availability.EndDate;
        availabilityToCreate.Negotiable = internshipToCreate.availability.Negotiable;

        // Add availability

        _internshipEntities.AddToAvailabilitySet(availabilityToCreate);

        //Add contact and availability entities to new internship entity

        i.contacts = contactToCreate;
        i.availability = availabilityToCreate;

        // Set internship entity values;

        i.UserID = internshipToCreate.UserID;
        //...
        //ommited for brevity
        //...
        i.Created = DateTime.Now;

        // Set the internship entity references to existing tables

        i.classificationsReference.EntityKey =
            new EntityKey("InternshipEntities.ClassificationSet", "ID", internshipToCreate.classifications.ID);
        i.educationReference.EntityKey =
            new EntityKey("InternshipEntities.EducationSet", "ID", internshipToCreate.education.ID);

        // Add internship and save

        _internshipEntities.AddToInternshipSet(i);
        _internshipEntities.SaveChanges();

        //commit transaction
        scope.Complete();

        return internshipToCreate;

    }
    catch (Exception e)
    {
        throw e;
    }
}

Answer 1

这段代码对我来说没有多大意义。在两种情况下，当您只需分配一个对象引用时，您将经历一个EntityKey。也就是说，更改以下内容：

internshipToCreate.contactsReference.EntityKey =
    new EntityKey("InternshipEntities.ContactSet", "ID", contactToCreate.ID);
internshipToCreate.availabilityReference.EntityKey =
    new EntityKey("InternshipEntities.AvailabilitySet", "ID", availabilityToCreate.ID);

...to：

internshipToCreate.contacts = contactToCreate;
internshipToCreate.availability = availabilityToCreate;

在其他两种情况下，您似乎正在尝试分配已经存在的对象的ID。在我看来，这两行即使成功了，也无济于事：

internshipToCreate.classificationsReference.EntityKey =
    new EntityKey("InternshipEntities.ClassificationSet", "ID", internshipToCreate.classifications.ID);
internshipToCreate.educationReference.EntityKey =
    new EntityKey("InternshipEntities.EducationSet", "ID", internshipToCreate.education.ID);

这样你就可以摆脱它们了。

当您进行这两个更改时会发生什么？

Answer 2

哈罗，

虽然我不确定问题出在哪里，但我有一个建议。传递给方法(internshipToCreate)的Internship对象用于将值传输到您在方法中实例化的其他实体(联系人、可用性)，并且它们的创建工作正常。

也许你应该试着用实习生做同样的事情？创建新的Internship对象，并通过从internshipToCreate对象获取所有值来设置它们，然后将新创建的对象传递给_internshipEntities.AddToInternshipSet方法。

您可能已经在internshipToCreate对象上设置了一些用于其他目的的值，其中一些值实际上是导致异常的原因。

我不知道你的业务逻辑是什么，但如果你把所有的东西放在一个事务下会更好，因为这样可能会发生前两个实体被创建，第三个实体不被创建的情况。