c# - c# linq lambda 使用多列加入三个列表

Question

我有这些列表:

var subjects = new List<SubjectModel>
        {
            new SubjectModel { subjId = 1, subjName = "Math" },
            new SubjectModel { subjId = 2, subjName = "Science" },
            new SubjectModel { subjId = 3, subjName = "History" },
            new SubjectModel { subjId = 4, subjName = "Language" }
        };

var quizzes = new List<QuizModel>
        {
            new QuizModel { quizId = 1, quizDate = DateTime.Parse("2016-11-25"), quizScore = 10, subjectId = 1 },
            new QuizModel { quizId = 2, quizDate = DateTime.Parse("2016-11-25"), quizScore = 15, subjectId = 1 },
            new QuizModel { quizId = 3, quizDate = DateTime.Parse("2016-11-25"), quizScore = 8, subjectId = 2 },
            new QuizModel { quizId = 4, quizDate = DateTime.Parse("2016-11-26"), quizScore = 13, subjectId = 1 },
            new QuizModel { quizId = 5, quizDate = DateTime.Parse("2016-11-26"), quizScore = 20, subjectId = 2 }
        };

var exams = new List<ExamModel>
        {
            new ExamModel { examId = 1, examDate = DateTime.Parse("2016-11-25"), examScore = 90, subjectId = 1 },
            new ExamModel { examId = 2, examDate = DateTime.Parse("2016-11-25"), examScore = 88, subjectId = 2 },
            new ExamModel { examId = 3, examDate = DateTime.Parse("2016-11-25"), examScore = 92, subjectId = 4 },
            new ExamModel { examId = , examDate = DateTime.Parse("2016-11-26"), examScore = 84, subjectId = 1 },

        };

var exercises = new List<ExerciseModel>
        {
            new ExerciseModel { exerciseId = 1, exerciseDate = DateTime.Parse("2016-11-25"), exerciseScore = 17, subjectId = 1 }, 
            new ExerciseModel { exerciseId = 2, exerciseDate = DateTime.Parse("2016-11-25"), exerciseScore = 15, subjectId = 2 },
            new ExerciseModel { exerciseId = 3, exerciseDate = DateTime.Parse("2016-11-26"), exerciseScore = 15, subjectId = 1 },
            new ExerciseModel { exerciseId = 4, exerciseDate = DateTime.Parse("2016-11-26"), exerciseScore = 12, subjectId = 4 },
            new ExerciseModel { exerciseId = 5, exerciseDate = DateTime.Parse("2016-11-26"), exerciseScore = 10, subjectId = 1 },
        };

我能够成功地将它们按日期和主题分组。

var allQuizzes = quizzes.GroupBy(qz => qz.quizDate, (q, values) =>
            new
            {
                Date = q,
                Quizzes = values.GroupBy(v => v.subjectId, (c, values2) => 
                    new { 
                        SubjectId = c, 
                        QuizSum = values2.Sum(v2 => v2.quizScore) 
                    })
            });

var allExercises = exercises.GroupBy(ex => ex.exerciseDate, (e, values) =>
            new {
                Date = e,
                Exercises = values.GroupBy(x => x.subjectId, (z, values2) =>
                    new {
                        SubjectId = z,
                        ExerSum = values2.Sum(r => r.exerciseScore)
                    })
            });

var allExams = exams.GroupBy(ex => ex.examDate, (e, values) =>
            new
            {
                Date = e,
                Exercises = values.GroupBy(x => x.subjectId, (z, values2) =>
                    new
                    {
                        SubjectId = z,
                        ExamSum = values2.Sum(r => r.examScore)
                    })
            });

但是，我需要加入所有三个以获得所有分数的总和。决赛 table 应该像这样显示。

-----------------------------------------------------------------
|      Date     |  Math  |  Science  |   History   |  Language  |
|   11/25/2016  |   132  |      111  |         0   |        92  |
|   11/26/2016  |   122  |       20  |         0   |        12  |
-----------------------------------------------------------------

我尝试加入它们，但它似乎无法通过多列加入。

Answer 1

我从所有 3 个集合结果中选择相同匿名类的形式(Andrei 在第一个答案中有相同的想法)，这使我可以将所有结果一起收集在所有列表中，而无需映射和转换。

var allQuiz = quizzes.GroupBy(x => new { x.subjectId, x.quizDate })
                     .Select(x => new {
                          Date = x.Key.quizDate, 
                          Subj = x.Key.subjectId, 
                          Sum = x.Sum(r=>r.quizScore)});

var allExam= exams.GroupBy(x => new { x.subjectId, x.examDate })
                     .Select(x => new {
                          Date = x.Key.examDate, 
                          Subj = x.Key.subjectId, 
                          Sum = x.Sum(r=>r.examScore)});

var allExc = exercises.GroupBy(x => new { x.subjectId, x.exerciseDate })
                     .Select(x => new {
                          Date = x.Key.exerciseDate, 
                          Subj = x.Key.subjectId, 
                          Sum = x.Sum(r=>r.exerciseScore)});

将所有结果组合在一起:

var all = allQuiz.ToList();
all.AddRange(allExam.ToList());
all.AddRange(allExc.ToList());

var result = all.GroupBy(x => new { x.Date, x.Subj })
                .Select(x => new { x.Key.Date, x.Key.Subj, Sum = x.Sum(s => s.Sum)});

var list = result.GroupBy(r => r.Date).Select(x => new {
       Date = x.Key, 
       Math = x.SingleOrDefault(t=>t.Subj==1)?.Sum ?? 0,
       Science = x.SingleOrDefault(t=>t.Subj==2)?.Sum ?? 0,
       History = x.SingleOrDefault(t=>t.Subj==3)?.Sum ?? 0,
       Language = x.SingleOrDefault(t=>t.Subj==4)?.Sum ?? 0,
       });

LinqPad 中的输出: