Question

I need help with trying to insert a record using MVC and Entity Framework. I have a dynamically created form which can contain many questions. When Editing, I want to delete the existing answers (which it does successfully) and insert new answers.

I am getting the following error:
Cannot insert explicit value for identity column in table ‘tblModeratorReportAnswers’ when IDENTITY_INSERT is set to OFF.

If I add the following line in my DbContext class
modelBuilder.Entity<QuestionAnswer>().Property(p => p.AnswerID).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity); I get this error:
A dependent property in a ReferentialConstraint is mapped to a store-generated column. Column: ‘AnswerID’.

Here’s my code that is doing the update

//
// POST: /Home/Edit/1
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Edit(FormCollection formCollection, int moderatorReportId)
{
    ModeratorReport reportToEdit = repository.GetModeratorReportById(moderatorReportId);
    List<QuestionAnswer> originalReportAnswers = repository.GetAllModeratorReportAnswers(moderatorReportId).ToList();

    foreach (QuestionAnswer answer in originalReportAnswers) {
        repository.DeleteAnswer(answer);
    }

    repository.Save();

    int sectionID;
    int questionID;

    foreach (string key in formCollection.AllKeys)
    {
        var value = formCollection[key.ToString()];

        Match m = Regex.Match(key, "section(\\d+)_question(\\d+)");

        if (m.Success) {
            QuestionAnswer newAnswer = new QuestionAnswer();

            sectionID = Convert.ToInt16(m.Groups[1].Value.ToString());
            questionID = Convert.ToInt16(m.Groups[2].Value.ToString());

            newAnswer.ModeratorReportID = moderatorReportId;
            newAnswer.QuestionID = questionID;
            newAnswer.Answer = value;
            repository.AddAnswer(newAnswer);
        }
    }

    repository.Save();

    reportToEdit.Status = "SUBJECTOFFICER SAVED";

    AuditItem auditItem = new AuditItem();
    auditItem.ModeratorReportID = moderatorReportId;
    auditItem.Status = "SUBJECTOFFICER SAVED";
    auditItem.AuditDate = DateTime.Now;
    auditItem.Description = "The Moderator report ID: " + moderatorReportId + " was saved.";
    auditItem.UserID = User.Identity.Name;

    db.Audit.Add(auditItem);

    repository.Save();

    return RedirectToAction("Details", new { id = moderatorReportId });
}

…and in my repository

//
// Persistance

public void Save()
{
    db.SaveChanges();
}

public void AddAnswer(QuestionAnswer answer)
{
    db.Answers.Add(answer);
    Save();
}

public void DeleteAnswer(QuestionAnswer answer) 
{
    db.Answers.Attach(answer);
    db.Answers.Remove(answer);
}

I have also checked all my Primary Keys, Foreign Keys and they are all ok. The Primary Keys are all set to ‘Is Identity’.

I’ve been trying to sort this problem out all day. I have no idea what to do to resolve it. If anyone can give my any advice, it’d be much appreciated.

Answer 1

Maybe it’s my inexperience with ASP.NET MVC and Entity Framework, but I have now resolved this issue by changing the logic of that I update the report.

Instead of deleting the answers and reinserting them. I now retrieve the answers and change Answer property to be the new answer. Then just use db.SaveChanges().

//
// POST: /Home/Edit/1
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Edit(FormCollection formCollection, int moderatorReportId)
{
    ModeratorReport reportToEdit = repository.GetModeratorReportById(moderatorReportId);
    List<QuestionAnswer> originalReportAnswers = repository.GetAllModeratorReportAnswers(moderatorReportId).ToList();

    int sectionID;
    int questionID;

    foreach (string key in formCollection.AllKeys)
    {
        var value = formCollection[key.ToString()];

        Match m = Regex.Match(key, "section(\\d+)_question(\\d+)");

        if (m.Success) {
            QuestionAnswer newAnswer = new QuestionAnswer();

            sectionID = Convert.ToInt16(m.Groups[1].Value.ToString());
            questionID = Convert.ToInt16(m.Groups[2].Value.ToString());

            foreach(QuestionAnswer answerToEdit in originalReportAnswers) {
                if (answerToEdit.QuestionID == questionID)
                {
                    answerToEdit.Answer = value;
                }
            }
        }
    }

    repository.Save();

    reportToEdit.Status = "SAVED";

    AuditItem auditItem = new AuditItem();
    auditItem.ModeratorReportID = moderatorReportId;
    auditItem.Status = "SAVED";
    auditItem.AuditDate = DateTime.Now;
    auditItem.Description = "The Moderator report ID was saved.";
    auditItem.UserID = User.Identity.Name;

    db.Audit.Add(auditItem);

    repository.Save();

    return RedirectToAction("Details", new { id = moderatorReportId });
}