当 IDENTITY_INSERT 设置为 OFF 时，无法在“DentalProcedures”中插入标识列的显式值。 EF代码优先

Question

I will try to keep this one short. Any help is welcome and appreciated!

I have 2 classes that have a many-to-many relationship and their composite key class. When I'm creating a new "appointment" I want to pick "dental procedures" that are in the system.

All works fine until I reach the AppointmentRepository where I try to save the newly created appointment. The error is as stated.

I tried to add the

[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]

or

[DatabaseGeneratedAttribute(DatabaseGeneratedOption.None)]

annotations above the DentalProcedureId property in the DentalProcedure class, but nothing works. Saved the changes and dropped tables, deleted all of the migrations etc.

DentalProcedure class:

public class DentalProcedure
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int DentalProcedureId { get; set; }
    [Required(ErrorMessage = "The name of the procedure must be specified")]
    public string ProcedureName { get; set; }
    [Required(ErrorMessage = "The price of the procedure must be specified")]
    public decimal ProcedurePrice { get; set; }
    public bool isEnabled { get; set; }

    public List<CustomerProcedure> CustomerProcedures { get; set; }
    public List<AppointmentProcedure> AppointmentProcedures { get; set; }
}

Appointment class:

public class Appointment
{
    [Key]
    public int AppointmentId { get; set; }
    [Required]
    public DateTime AppointmentStart { get; set; }
    [Required]
    public DateTime AppointmentEnd   { get; set; }

    [Required]
    public string Title { get; set; }
    public string ProcedureDescription { get; set; } 

    public int CustomerId { get; set; }
    public Customer Customer { get; set; }

    public int WorkDaysId { get; set; }
    public WorkDays WorkDays { get; set; }

    public List<AppointmentProcedure> AppointmentProcedures { get; set; }
}

AppointmentProcedure class:

public class AppointmentProcedure
{
    public int AppointmentId { get; set; }
    public Appointment Appointment { get; set; }

    public int DentalProcedureId { get; set; }
    public DentalProcedure DentalProcedure { get; set; }

    public bool ProcedureAppointmentCanceled { get; set; }
}

Home controller:

 Appointment appointment = new Appointment
                {
                    AppointmentStart = model.AppointmentStart,
                    AppointmentEnd = model.AppointmentEnd,
                    Title = model.Title,
                    ProcedureDescription = model.ProcedureDescription,
                    CustomerId = Id,
                    WorkDaysId =  workkWeek.WorkDaysId,
                };

foreach (var proc in model.DentalProcedures)
{
    if (proc.isEnabled)
    {
        appointment.AppointmentProcedures = new List<AppointmentProcedure>
                        {
                            new AppointmentProcedure
                            {
                                Appointment = appointment,
                                DentalProcedure = proc,
                                ProcedureAppointmentCanceled = false
                            }
                        };
    }
}

_appointment.CreateAppointment(appointment);

And the error:

Thanks once more in advance.

PS: I'm still learning so if I forgot to mention something, I apologize in advance!

Answer 1

Entity Framework needs to track the object in the database so you need to either attach or (what I usually prefer to do) load it from the database. Here's the changed code:

foreach (var proc in model.DentalProcedures)
{
    if (proc.isEnabled)
    {
        //assuming the DBSet is called Procedures
        var dbProc = await db.Procedures.FirstOrDefaultAsync(p => p.DentalProcedureId == id));
        appointment.AppointmentProcedures = new List<AppointmentProcedure>
                        {
                            new AppointmentProcedure
                            {
                                Appointment = appointment,
                                DentalProcedure = dbProc, //now set the loaded entity
                                ProcedureAppointmentCanceled = false
                            }
                        };
    }
}