public void RunDemo()
{
/*
* IEnumerable<Singer> singers = DemoCollections.GetSingers();
* IEnumerable<Concert> concerts = DemoCollections.GetConcerts();
*
* var singerConcerts = singers.GroupJoin(concerts, s => s.Id, c => c.SingerId, (s, co) => new
* {
* Id = s.Id
* , SingerName = string.Concat(s.FirstName, " ", s.LastName)
* , ConcertCount = co.Sum(c => c.ConcertCount)
* });
*
* foreach (var res in singerConcerts)
* {
* Console.WriteLine(string.Concat(res.Id, ": ", res.SingerName, ", ", res.ConcertCount));
* }
*/
//1st silly try
IEnumerable <Student> students = DemoCollections.GetStudents();
IEnumerable <StudentScore> studentScores = DemoCollections.GetScores();
IEnumerable <IGrouping <string, StudentScore> > subjectGroupings = studentScores
.GroupBy(score => score.Subject);
foreach (var subjectGroup in subjectGroupings)
{
Console.WriteLine($"Subject: {subjectGroup.Key}");
Console.WriteLine($"Total points across all students: {subjectGroup.Sum(g => g.Points)}");
}
var totalStudentScores = students.GroupJoin(studentScores
, student => student.Id, score => score.StudentId, (student, scores) =>
new
{
Id = student.Id,
StudentName = student.Name,
TotalScore = scores.Sum(s => s.Points)
}
);
foreach (var student in totalStudentScores)
{
Console.WriteLine($"ID: {student.Id}, Name: {student.StudentName}, Total score: {student.TotalScore} ");
}
//grouped try
var groupedStudentScores = students.GroupJoin(studentScores
, student => student.Id, score => score.StudentId, (student, scores) =>
{
var subjectGroups = scores.Where(score => score.StudentId == student.Id)
.GroupBy(score => score.Subject);
Dictionary <string, int> scoresDictionary = new Dictionary <string, int>();
foreach (var subjectGroup in subjectGroups)
{
string subjectName = subjectGroup.Key;
int subjectScoreTotal = subjectGroup.Sum(s => s.Points);
scoresDictionary[subjectName] = subjectScoreTotal;
}
return(new
{
Id = student.Id,
StudentName = student.Name,
Scores = scoresDictionary
});
}
);
foreach (var student in groupedStudentScores)
{
Console.WriteLine($"ID: {student.Id}, Name: {student.StudentName}, Total score by subject: {JsonConvert.SerializeObject(student.Scores)} ");
}
}