Question

我有一个主表 - 问题和详细信息表 - 答案。一个问题可以有多个答案。使用Entity Framework插入答案的正确方法是什么？

[Table("question")]
public class Question
{
    [Key]
    [Column("idquestion")]
    public int Id { get; set; }

    [Column("name")]
    public string Name { get; set; }

    [Column("locked")]
    public bool Locked { get; set; }

    [Column("answered")]
    public bool Answered { get; set; }

    [Column("skipped")]
    public bool Skipped { get; set; }

    [Column("skipped_emails")]
    public string SkippedEmails { get; set; }

    [Column("idspecialty")]
    public int? SpecialtyId { get; set; }

    public virtual ICollection<Answer> Answers { get; set; }
}

答案表：

 [Table("answer")]
public class Answer
{
    [Key]
    [Column("idanswer")]
    public int Id { get; set; }

    [Column("name")]
    public string Name { get; set; }

    [Column("answered_by")]
    public string AnsweredBy { get; set; }

    [Column("answered_on")]
    public DateTime? AnsweredOn { get; set; }

    [Column("idquestion")]
    [ForeignKey("Question")]
    public int QuestionId { get; set; }

    public Question Question { get; set; }
}

我在代码表中插入行的代码不起作用：

using(var context = new QnAContext())
        {
            var answer = new Answer();
            answer.Name = tbAnswer.Text;
            answer.AnsweredBy = this.User.Identity.Name;
            answer.AnsweredOn = DateTime.Now;

            int questionId = int.Parse(hdnQuestion.Value);
            var question = context.Questions.SingleOrDefault(q => q.Id == questionId);
            if(question!=null)
            {
                question.SpecialtyId = int.Parse(ddlSpecialty.SelectedItem.Value);
                question.Answered = true;
                answer.Question = question;
            }

            context.SaveChanges();
        }

Answer 1

将answer.Question = question;替换为question.Answers.Add(answer);，并确保将.Include(q => q.Answers)放在上下文的Questions集合中，即：

int questionId = int.Parse(hdnQuestion.Value);

var answer = new Answer
{
    Name = tbAnswer.Text,
    AnsweredBy = this.User.Identity.Name,
    AnsweredOn = DateTime.Now
};

using(var context = new QnAContext())
{
    for (var question in context.Questions
                                .Include(q => q.Answers)
                                .Where(q => q.Id == questionId))
    {
        question.SpecialtyId = int.Parse(ddlSpecialty.SelectedItem.Value);
        question.Answered = true;
        question.Answers.Add(answer);
    }

    context.SaveChanges();
}

使用Entity Framework添加详细信息行

1 个答案: