Cannot insert explicit value for identity column while updating entity - entity-framework

Question

I am using ASP.NET Boilerplate template.
I want to update Details table, which contains more than one item. If an item exists, it must update, otherwise a new one must be added and all other entries relating to Master primary key in Details table must be deleted. But it is showing an error:
Cannot insert explicit value for identity column in table
'SemesterDetails' when IDENTITY_INSERT is set to OFF
This is the Master table:
public class StudentDegreeCore : Entity<int>
{
[StringLength(150)]
[Required(ErrorMessage = "Enter Degree College ")]
public string DegreeCollege { get; set; }
[Required()]
public string CollegeID { get; set; }
[StringLength(7, ErrorMessage = "The {0} must be at least {2} characters long.", MinimumLength = 7)]
[Required(ErrorMessage = "Enter 10th Pass Year")]
public string CommencementYear { get; set; }
public List<StudentSemesterCore> SemesterDetails { get; set; }
}
This is the Details table, represented by the StudentSemesterCore class:
public class StudentSemesterCore
{
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
[StringLength(150)]
[Required(ErrorMessage = "Enter Year/Semester")]
public string YearOrSemester { get; set; }
[Required()]
public virtual int StudentDegreeID { get; set; }
[ForeignKey("StudentDegreeID")]
public virtual StudentDegreeCore StudentDegreeCore { get; set; }
[StringLength(4, ErrorMessage = "The {0} must be at least {2} characters long.", MinimumLength = 4)]
[Required(ErrorMessage = "Enter Semester Status")]
public string Status { get; set; }
[DisplayName("% of Marks")]
[RegularExpression(#"\d+(\.\d{1,2})?", ErrorMessage = "Numbers With Two decimal Place Allowed")]
public decimal MarkPercentage { get; set; }
}
This is the Update code:
_studentdegreeRepository.Update(st);
CurrentUnitOfWork.SaveChanges();
It shows an error when SaveChanges is called. Actually, I want to update the details if the same value exists, otherwise add new one and all other data relating to the same StudentDegreeID must be removed.

Answer 1

StudentSemesterCore is not derived from Entity.
You don't need to put Id property in StudentSemesterCore. Remove it.
Add StudentDegreeCoreId to StudentSemesterCore as foreign key reference.

Answer 2

I tried this
public override async Task<StudentDegreeDto> Create(StudentDegreeCreateDto input)
{
//CheckCreatePermission();
StudentDegreeCore st = new StudentDegreeCore();
try
{
StudentDegreeCore core = new StudentDegreeCore()
{
Id = input.Id,
Address1 = input.Address1,
Address2 = input.Address2,
City = input.City,
CollegeID = input.CollegeID,
CommencementYear = input.CommencementYear,
CompletionYear = input.CompletionYear,
CurrentYear = input.CurrentYear,
DegreeCollege = input.DegreeCollege,
DegreeId = input.DegreeId,
OverallPercent = input.OverallPercent,
PinCode = input.PinCode,
PostBox = input.PostBox,
State = input.State,
StreamId = input.StreamId,
UserId = input.UserId
};
core.SemesterDetails = new List<StudentSemesterCore>();
foreach (var items in input.SemesterDetails)
{
core.SemesterDetails.Add(new StudentSemesterCore()
{
GPA = items.GPA,
MarkPercentage = items.MarkPercentage,
Status = items.Status,
UserId = items.UserId ,
Id = items.Id,
StudentDegreeID = items.StudentDegreeID ,
YearOrSemester = items.YearOrSemester,
LastModificationTime = DateTime.Now,
CreationTime = DateTime.Now
});
}
var student = core; //ObjectMapper.Map<StudentDegreeCore>(input);
long uid = (AbpSession.UserId == null) ? 0 : Convert.ToInt64(AbpSession.UserId);
st = _studentRepository.Get(student.Id);
if (st != null && st.Id > 0)
{
st.DegreeCollege = student.DegreeCollege;
st.CollegeID = student.CollegeID;
st.CommencementYear = student.CommencementYear;
st.CompletionYear = student.CompletionYear;
st.LastModificationId = Convert.ToInt32(AbpSession.UserId);
st.LastModificationTime = DateTime.Now;
st.StreamId = student.StreamId;
st.DegreeId = student.DegreeId;
st.CurrentYear = student.CurrentYear;
st.OverallPercent = student.OverallPercent;
st.PinCode = student.PinCode;
st.PostBox = student.PostBox;
st.State = student.State;
st.Address1 = student.Address1;
st.Address2 = student.Address2;
st.City = student.City;
st.SemesterDetails = new List<StudentSemesterCore>();
//st.SemesterDetails = student.SemesterDetails;
_studentRepository.Update(st);
foreach (var items in student.SemesterDetails)
{
_studentSemesterRepository.InsertOrUpdate(items);
}
//_studentRepository.Update(st);
CurrentUnitOfWork.SaveChanges();
}
else
{
student.UserId = Convert.ToInt32(AbpSession.UserId);
student.CreationId = Convert.ToInt32(AbpSession.UserId);
_studentRepository.Insert(student);
CurrentUnitOfWork.SaveChanges();
}
}
catch (Exception ex)
{
}
StudentDegreeDto studentDegreeDto = new StudentDegreeDto()
{
Id = input.Id,
Address1 = input.Address1,
Address2 = input.Address2,
City = input.City,
CollegeID = input.CollegeID,
CommencementYear = input.CommencementYear,
CompletionYear = input.CompletionYear,
CurrentYear = input.CurrentYear,
DegreeCollege = input.DegreeCollege,
DegreeId = input.DegreeId,
OverallPercent = input.OverallPercent,
PinCode = input.PinCode,
PostBox = input.PostBox,
State = input.State,
StreamId = input.StreamId,
UserId = input.UserId
};
studentDegreeDto.SemesterDetails = new List<StudentSemesterDto>();
foreach (var items in input.SemesterDetails)
{
studentDegreeDto.SemesterDetails.Add(new StudentSemesterDto()
{
GPA = items.GPA,
MarkPercentage = items.MarkPercentage,
Status = items.Status,
YearOrSemester = items.YearOrSemester,
LastModificationTime = DateTime.Now,
CreationTime = DateTime.Now
});
}
return studentDegreeDto;
}