C#linq集团多次

我有一个物体测验，看起来像：

public class Quiz
{     
    public int Id { get; set; }          
    public ICollection<MathQuiz> MathQuizzes { get; set; }     
}

public class MathQuiz
{

    public int Id { get; set; }

    public int QuizId{ get; set; }
    public Quiz Quiz{ get; set; }

    public int AnswerId { get; set; }
    public Answer Answer { get; set; }

    public int TagId{ get; set; }
    public Tag Tag { get; set; }

    public bool IsCorrect { get; set; }

}

并且有一个对象（UserQuizzes）看起来像：

public class UserQuizes
    {
        public int Id { get; set; }


        public int UserId { get; set; }
        public User User { get; set; }


        public int QuizId { get; set; }
        public Quiz Quiz { get; set; }

}

UserQuizzes只是表示用户和quizzes之间的多对多关系的类。 这是一个示例数据：

     List<Quiz> quizzes = new List<Quiz>();
        quizzes.Add(new Quiz{ Id = 1, MathQuizzes = new List<MathQuiz>{ 
                  new MathQuiz { AnswerId = 58, TagId = 1, IsCorrect = false },  
                  new MathQuiz { AnswerId = 26, TagId = 2, IsCorrect = true }, 
                  new MathQuiz { AnswerId = 57, TagId = 3, IsCorrect = true },

                  new Quiz{ Id = 2, MathQuizzes = new List<MathQuiz>{ 
                  new MathQuiz { AnswerId = 59, TagId = 1, IsCorrect = false },  
                  new MathQuiz { AnswerId = 87, TagId = 2, IsCorrect = true }, 
                  new MathQuiz { AnswerId = 25, TagId = 3, IsCorrect = true }, });

    List<UserQuizzes> userQuizzes = new List<UserQuizzes>();
        userQuizzes.Add(new Quiz{ QuizId = 1, UserId = 1},
        userQuizzes.Add(new Quiz{ QuizId = 2, UserId = 1});

---

您发布的代码有拼写错误，但基本思想如下：

var query =
    from q in quizzes
    from mq in q.MathQuizzes
    join uq in userQuizzes on q.Id equals uq.QuizId
    group mq by mq.TagId into g
    select new
    {
        TagId = g.Key,
        Correct = g.Sum(e => e.IsCorrect ? 1 : 0),
        Incorrect = g.Sum(e => e.IsCorrect ? 0 : 1)
    };

---

基本上，您需要通过加入数据集来获得有效的源集，并执行常规的分组/计算聚合。

键入错误，我更新了Questionit，它只在一个简单的查询中工作，没有foreach循环。谢谢你很好的解决方案！你是否必须参加

用户测验

？你不需要它的任何信息。是的，我不需要，我正在使用include-eager-loading做同样的事情

var query =
    from q in quizzes
    from mq in q.MathQuizzes
    join uq in userQuizzes on q.Id equals uq.QuizId
    group mq by mq.TagId into g
    select new
    {
        TagId = g.Key,
        Correct = g.Sum(e => e.IsCorrect ? 1 : 0),
        Incorrect = g.Sum(e => e.IsCorrect ? 0 : 1)
    };