使用外键插入许多值

Question

I have two table

questionId is foreign key of Questions's Id.

I'm trying to save 4 answer in "Answers" table. Title is question's title and it must have 4 answer.

How can i insert 4 Answer which is connected by foreign key?

I have tried this:

QuizEntities quiz = new QuizEntities();
Question question = new Question();
Answer answer = new Answer();

question.Title = titleBox.Text;
question.ImageURL = "../Uploads/" + PhotoBox.Text;


 answer.Answer1 = firstAnswer.Text;
 answer.Answer1 = secondAnswer.Text;
 answer.Answer1 = thirdAnswer.Text;
 answer.Answer1 = fourthAnswer.Text;
 answer.questionId = question.Id;
 if (firstCheckBox.Checked)
 {
   answer.IsCorrect = true;
 }
 else
 {
   answer.IsCorrect = false;
 }

 quiz.Questions.Add(question);
 quiz.Answers.Add(answer);
 quiz.SaveChanges();

but using this I can insert only one value. How can I solve it?

Answer 1

Just create four answers and insert them all, you can create a function to make the code more readable.

private static Answer CreateAnswer (
    int id, string answer, bool isCorrect, int questionId)
{    
    var answer = new Answer
    {
        Id = id,
        Answer = answer,
        IsCorrect = isCorrect,
        questionId = questionId
    };
    return answer;
}

Then add a question with for answers by assigning temporary key.

using (var quiz = new QuizEntities())
{
    var qId = 1;
    var question = new Question
    {
        Id = qId,
        title = titleBox.Text,
        ImageURL = "../Uploads/" + PhotoBox.Text
    };

    quiz.Questions.Add(question);
    quiz.Answers.Add(
        CreateAnswer(1, firstAnswer.Text, (bool)firstCheckBox.Checked, qId));
    quiz.Answers.Add(
        CreateAnswer(2, secondAnswer.Text, (bool)secondCheckBox.Checked, qId));
    quiz.Answers.Add(
        CreateAnswer(3, thirdAnswer.Text, (bool)thirdCheckBox.Checked, qId));
    quiz.Answers.Add(
        CreateAnswer(4, fourthAnswer.Text, (bool)fourthCheckBox.Checked, qId));
    quiz.SaveChanges();
}

Tips:

• Wrap the context with using to make sure that it's disposed properly.
• Temporary key can be used to create relationship between principal and dependent before the entities are inserted.

Answer 2

If you want to add exactly four values, you need to create four Answer objects and for each of those assign the correct question ID.

Without testing this with compiler, I think you are looking for something like this;

QuizEntities quiz = new QuizEntities();
Question question = new Question();
Answer answer = new Answer();

question.Title = titleBox.Text;
question.ImageURL = "../Uploads/" + PhotoBox.Text;
 quiz.Questions.Add(question);

//Add first answer.
 answer.Answer = firstAnswer.Text;
 if (firstCheckBox.Checked)
 {
   answer.IsCorrect = true;
 }
 else
 {
   answer.IsCorrect = false;
 }

 answer.questionId = question.Id;
 quiz.Answers.Add(answer);

//Add second answer.
answer = new Answer();
 answer.Answer = secondAnswer.Text;
 if (secondCheckBox.Checked)
 {
   answer.IsCorrect = true;
 }
 else
 {
   answer.IsCorrect = false;
 }

 answer.questionId = question.Id;
 quiz.Answers.Add(answer);


//... add third and fourth as well.
 quiz.SaveChanges();