Question

我在使用LINQ时遇到问题，我想知道存储库中是否存在此代码的快速解决方案

GetCompletePackQuestion(int id)
    {
        var query = from q in DbSet where q.id == id
                    join a in DbContext.Set<answers>() on id equals a.question_id
                    join cc in DbContext.Set<correct_answers>() on id equals cc.question_id
                    select new CompletePackModel
                    {
                        Id = q.id,
                        Question = q.question,
                        CorrectAnswer = cc.answers.id,
                        Answers = q.answers.Select(ans => ans.answer)
                    };

        return query.SingleOrDefault();
    }

CompletePackModel将Answers属性作为字符串列表.. 所以问题是：一个问题有很多答案，所以q.id是一个int，问一个字符串，answer_id一个id（我真的应该把表中的字符串连接到那个id）...最后一个一个a.answer应该是一个清单......

有没有办法解决这个问题？

由于

为什么它会在查询中给出3个结果而不是一个？

Answer 1

我假设你正在使用Entity Framework（基于我看到的DbContext对象）。在这种情况下，您的问题类应该已经有一组答案。然后你需要做类似的事情：

select new CompletePackModel
{
  Id = q.id,
  Question = q.question,                            
  CorrectAnswer = from answ in DbContext.Set<answers>() where answ.id == a.id select answ.answer,
  Answers = q.answers.Select(a => a.answer).ToList()
};

Answer 2

这会起作用吗？

var query = from q in DbContext.Set<questions>()
                join a in DbContext.Set<answers>() on q.id equals a.question_id
                join cc in DbContext.Set<correct_answers>() on q.id equals cc.question_id
                select new CompletePackModel
                {
                    Id = q.id,
                    Question = q.question,                            
                    CorrectAnswer = cc.answer,
                    Answers = DbContext.Set<answers>().Where(answ => answ.question_id == q.id).ToList()
                };

LINQ连接查询中的列表

2 个答案: