LINQ的List內連接查詢

Question

我同時使用LINQ面臨的一個問題，我想知道是否有這個代碼庫

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(); 
    } 

的CompletePackModel內快速的解決方案給出了答案財產一個字符串列表.. 所以問題是：有一個問題有很多答案，所以雖然q.id是一個int，問一個字符串和answer_id一個id（嗯，我真的應該把表中的字符串連接到ID）...最後一個a.answer應該是一個清單...

有沒有一種方法可以解決這個問題？

感謝

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爲什麼它給我3結果在查詢，而不是一個？

Answer 1

我假設你正在使用實體框架（基於我看到的DbContext對象）。在這種情況下，您的問題類應該已經有一系列答案。然後你需要做類似的事情：

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

這會做詭計嗎？

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() 
       };