public int GetTotalStudentGradesFromACourse(Course course)
{
courseSubjectService = new CourseSubjectService();
gradeService = new GradeService();
studentService = new StudentService();
List <Student> studentsRegistered = studentService.GetStudentsRegisteredInACourse(course);
IEnumerable <StudentSubject> registeredStudentsSubjects = from s in studentsRegistered
join ss in db.StudentSubjects
on s.ID equals ss.StudentID
select ss;
int sumOfGrades = 0;
foreach (StudentSubject studentSubject in registeredStudentsSubjects.ToList())
{
if (studentSubject.Student.isEnrolled && studentSubject.Grade != null)
{
sumOfGrades = sumOfGrades + gradeService.ConvertGradeToInt(studentSubject.Grade);
}
}
return(sumOfGrades);
}
public Grade?GetStudentAverageGrade(int id)
{
gradeService = new GradeService();
IEnumerable <Grade?> totalGrades = from ss in db.StudentSubjects.ToList()
join s in db.Students.ToList()
on ss.StudentID equals s.ID
where s.isEnrolled
where s.ID == id
select ss.Grade;
List <Grade?> realTotalGrades = new List <Grade?>();
foreach (Grade?grade in totalGrades)
{
if (grade.HasValue)
{
realTotalGrades.Add(grade);
}
}
int totalGradesInInt = gradeService.ConvertAllGradesToInt(totalGrades.ToList());
if (realTotalGrades.ToList().Count != 0)
{
decimal average = totalGradesInInt / realTotalGrades.ToList().Count;
int roundedAverage = (int)Math.Round(average);
Grade?averageInGrade = gradeService.ConvertIntToGrade(roundedAverage);
}
return(null);
}
public Grade?GetStudentAverageGradePerCourse(Course course)
{
studentService = new StudentService();
subjectService = new SubjectService();
studentSubjectService = new StudentSubjectService();
gradeService = new GradeService();
int studentsAverageGrade;
int studentsAverageRounded;
Grade?averageGrade;
List <Subject> subjectsFromACourse = subjectService.GetSubjectsFromACourse(course);
int numberOfSubjectsInACourse = subjectsFromACourse.Count();
int numberOfStudentsRegisteredInACourse = studentService
.GetStudentsRegisteredInACourse(course).Count();
int studentsTotalGrades = studentSubjectService
.GetTotalStudentGradesFromACourse(course);
int numberOfStudentSubjectsGraded = GetNumberOfStudentsSubjectsGradedInACourse(subjectsFromACourse);
if (numberOfSubjectsInACourse != 0 && numberOfStudentSubjectsGraded != 0)
{
studentsAverageGrade =
studentsTotalGrades / numberOfStudentSubjectsGraded;
}
else
{
studentsAverageGrade = 0;
}
studentsAverageRounded = (int)Math.Round((decimal)studentsAverageGrade);
averageGrade = gradeService.ConvertIntToGrade(studentsAverageRounded);
return(averageGrade);
}
public StudentSubject ChangeGrade(int id, StudentSubject studentSubject)
{
gradeService = new GradeService();
if (gradeService.ConvertGradeToInt(studentSubject.Grade - 2) < 0 ||
gradeService.ConvertGradeToInt(studentSubject.Grade - 2) > 4)
{
return(null);
}
StudentSubject newStudentSubject = db.StudentSubjects.Find(id);
if (newStudentSubject == null)
{
return(null);
}
newStudentSubject.Grade = studentSubject.Grade;
db.SaveChanges();
return(newStudentSubject);
}