I have a problem, imagine the following situation where I receive the following records from the database:

Now imagine I have the following class:

public class test 
{
    public int idStudent { get; set; }
    public List<StudentGrade> StudentGrades { get; set; }
}

public class StudentGrade
{
    public string className { get; set; }
    public int startTime { get; set; }
    public int endTime { get; set; }
}

Using Linq, how would I create this same class where I only have a "test" class with a list of StudentGrades?

I tried to do it like this, but I don't know how to create a list:

  var allResult = _getAllClass.FindAll();
        var resul = allResult.GroupBy(x => x.studentID)
                           .Select(s => new test
                           {
                               idStudent = s.Select(ss => ss.studentID).FirstOrDefault(),
                               StudentGrades = /// 

                           }

CodePudding user response：

 var result = allResult.GroupBy(x => x.studentID, (k, g) => new test
            {
                idStudent = k,
                StudentGrades = g.Select(r => new StudentGrade
                {
                    className = r.className,
                    startTime = r.startTime,
                    endTime = r.endTime,
                }).ToList()
            }).ToList();

CodePudding user response：

You need to process the group to create the List inside the testvar

allResult = _getAllClass.FindAll();
var result = allResult.GroupBy(x => x.studentID)
                      .Select(cg => new test {
                          idStudent = cg.Key,
                          StudentGrades = cg.Select(c => new StudentGrade {
                              className = c.className,
                              startTime = c.startTime,
                              endTime = c.endTime,
                           })
                           .ToList()
                       })
                       .ToList();