一次在Entity中插入多个相关表

Question

I have three tables that are connected by foreign keys. I am trying to insert 1 row in the question table and two rows in the other two tables. I am getting the error 'Insert statement conflict with Foreign Key constraint' Thank you in advance for the help

public void setMultiAnswer()
{
try
{
    string question = "Question 1"
    responsesList.Add("Answer1");
    responsesList.Add("Answer2");
    questionResponsesList.Add(false);
    questionResponsesList.Add(true);

    using (Entities testEntity = new Entities())
    {
        Question questionObj = new Question();
        questionObj.Question1 = question;
        questionObj.CreatedBy = "test";
        questionObj.CreatedDate = DateTime.Now;

        QuestionRespons questionResponsesObj = new QuestionRespons();
        // fill response
        foreach (var questionResponse in questionResponsesList)
        {
            questionResponsesObj.CorrectResponse = questionResponse;
        }

        questionObj.QuestionResponses.Add(questionResponsesObj);

        Response responseObj = new Response();

        // fill response 
        foreach (var response in responsesList)
        {
             responseObj.Response1 = response;
             responseObj.CreatedBy = "test";
             responseObj.CreatedDate = DateTime.Now;
        }
        questionResponsesObj.Response = responseObj;

        testEntity.Questions.Add(questionObj);
        testEntity.SaveChanges();
    }
}
catch (Exception ex)
{
    Console.Write(ex);
}

Answer 1

It sounds like your question id is autogenerated. In this case int questionId = questionObj.QuestionID; will only work after the SaveChanges() call.

In general if you have an EntitySet with foreign keys it is easier to use the navigation properties instead of building id references yourself.

Question questionObj = new Question();
questionObj.CreatedBy = "Test";
questionObj.CreatedDate = DateTime.Now;

QuestionRespons questionResponsesObj = new QuestionRespons();
// fill question response here
questionObj.QuestionResponses.Add(questionResponseObj);

Response responseObj = new Response();
// fill your response here
questionResponsesObj.Response = reponseObj;
// if you do the above in your loop you should be fine

testEntity.Questions.Add(questionObj);
testEntity.SaveChanges();

To match your example:

public void setMultiAnswer()
{
    try
    {
        string question = "Question 1"
        responsesList.Add("Answer1");
        responsesList.Add("Answer2");
        questionResponsesList.Add(false);
        questionResponsesList.Add(true);

        using (Entities testEntity = new Entities())
        {
            Question questionObj = new Question();
            questionObj.Question1 = question;
            questionObj.CreatedBy = "Test";
            questionObj.CreatedDate = DateTime.Now;
            testEntity.Questions.Add(questionObj);

            for (int i = 0; i < responsesList.Count; i++)
            {
                // i am not sure about your relation here, but i assume you require one QuestionResponse per response
                // which is why a moved the line of code
                QuestionRespons questionResponsesObj = new QuestionRespons();
                questionObj.QuestionResponses.Add(questionResponsesObj);

                Response responseObj = new Response();
                responseObj.Response1 = responsesList.ElementAt(i);
                responseObj.CreatedBy = "Test";
                responseObj.CreatedDate = DateTime.Now;

                if (!string.IsNullOrEmpty(responseObj.Response1))
                {
                    questionResponsesObj.Response = responseObj;
                    questionResponsesObj.CorrectResponse = questionResponsesList.ElementAt(i);
                }

            }
            testEntity.SaveChanges();
        }
    }
    catch (Exception ex)
    {
        Console.Write(ex);
    }
}

Answer 2

Change the order of

int questionId = questionObj.QuestionID;
testEntity.SaveChanges();

into

testEntity.SaveChanges();
int questionId = questionObj.QuestionID;

You created a new instance questionObj which should have a default ID of 0. Only AFTER calling SaveChanges() the ID should be assigned the newly assigned actual ID value.

So, what happens here, is that you memorize questionId with the default value of 0 instead of the real ID. As a conseqence, the relations between questions and responses will always be wrong.

Answer 3

If I were you I would remove this QuestionResponse table, to keep only Question and Response. Use the navigation properties instead of directly setting the foreign key.

    Question questionObj = new Question
    {
        Text = question,
        CreatedBy = "Test",
        CreatedDate = DateTime.Now
    };

    foreach(var response in responsesList.Where(x => !string.IsNullOrEmpty(x)))
    {
        Response responseObj = new Response
        {
            Text = response,
            IsCorrect = true,
            CreatedBy = "Test",
            CreatedDate = DateTime.Now
        }

        questionObj.Add(responseObj);
    }

    testEntity.Questions.Add(questionObj);
    testEntity.SaveChanges();