EF 4.1 - code首先 - JSON循环引用序列化错误

问题描述

我得到一个循环引用序列化错误，虽然，据我所知，我没有任何循环引用。我从数据库中检索一组订单，并将它们发送到客户端为JSON。所有code如下图所示。

这是错误：

My classes are as follows:

Order

public class Order
{
    [Key]
    public int OrderId { get; set; }

    public int PatientId { get; set; }
    public virtual Patient Patient { get; set; }

    public int CertificationPeriodId { get; set; }
    public virtual CertificationPeriod CertificationPeriod { get; set; }

    public int AgencyId { get; set; }
    public virtual Agency Agency { get; set; }

    public int PrimaryDiagnosisId { get; set; }
    public virtual Diagnosis PrimaryDiagnosis { get; set; }

    public int ApprovalStatusId { get; set; }
    public virtual OrderApprovalStatus ApprovalStatus { get; set; }

    public int ApproverId { get; set; }
    public virtual User Approver { get; set; }

    public int SubmitterId { get; set; }
    public virtual User Submitter { get; set; }

    public DateTime ApprovalDate { get; set; }

    public DateTime SubmittedDate { get; set; }
    public Boolean IsDeprecated { get; set; }
}

Patient

public class Patient
{
    [Key]
    public int PatientId { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string MiddleInitial { get; set; }
    public bool IsMale;
    public DateTime DateOfBirth { get; set; }

    public int PatientAddressId { get; set; }
    public Address PatientAddress { get; set; }

    public bool IsDeprecated { get; set; }
}

Certification Period

public class CertificationPeriod
{
    [Key]
    public int CertificationPeriodId { get; set; }
    public DateTime startDate { get; set; }
    public DateTime endDate { get; set; }
    public bool isDeprecated { get; set; }
}

Agency

public class Agency
{
    [Key]
    public int AgencyId { get; set; }
    public string Name { get; set; }

    public int PatientAddressId { get; set; }
    public virtual Address Address { get; set; }
}

Diagnosis

public class Diagnosis
{
    [Key]
    public int DiagnosisId { get; set; }
    public string Icd9Code { get; set; }
    public string Description { get; set; }
    public DateTime DateOfDiagnosis { get; set; }
    public string Onset { get; set; }
    public string Details { get; set; }
}

OrderApprovalStatus

public class OrderApprovalStatus
{
    [Key]
    public int OrderApprovalStatusId { get; set; }
    public string Status { get; set; }
}

User

public class User
{
    [Key]
    public int UserId { get; set; }
    public string Login { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string NPI { get; set; }
    public string Email { get; set; }

}

Address

public class Address
{
    [Key]
    public int AddressId { get; set; }
    public string StreetAddress { get; set; }
    public string City { get; set; }
    public string State { get; set; }
    public string Zip { get; set; }
    public string Phone { get; set; }
    public string Title { get; set; }
    public string Label { get; set; }
}

The code that executes the serialization is here:

Excerpt from OrderController

    public ActionResult GetAll()
    {
        return Json(ppEFContext.Orders, JsonRequestBehavior.AllowGet);
    }

Thanks

解决方案

You could try to remove the virtual keyword from all navigation properties to disable lazy loading and proxy creation and then use eager loading instead to load the required object graph explicitely:

public ActionResult GetAll()
{
    return Json(ppEFContext.Orders
                           .Include(o => o.Patient)
                           .Include(o => o.Patient.PatientAddress)
                           .Include(o => o.CertificationPeriod)
                           .Include(o => o.Agency)
                           .Include(o => o.Agency.Address)
                           .Include(o => o.PrimaryDiagnosis)
                           .Include(o => o.ApprovalStatus)
                           .Include(o => o.Approver)
                           .Include(o => o.Submitter),
        JsonRequestBehavior.AllowGet);
}

Referring to your previous post it looks like your application isn't relying on lazy loading anyway because you introduced there the virtual properties to load the object graph lazily, possibly causing now the serialization trouble.

Edit

It's not necessary to remove the virtual keyword from the navigation properties (which would make lazy loading completely impossible for the model). It's enough to disable proxy creation (which disables lazy loading as well) for the specific circumstances where proxies are disturbing, like serialization:

ppEFContext.Configuration.ProxyCreationEnabled = false;

This disables proxy creation only for the specific context instance ppEFContext.

(I've just seen, @WillC already mentioned it here. Upvote for this edit please to his answer.)

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