/// <summary>
/// Adds the student to the course with the given ID
/// If no course/student is found, an Object not found exception is thrown.
/// </summary>
/// <param name="ID"></param>
/// <param name="student"></param>
/// <returns></returns>
public StudentDTO AddStudentToCourse(int ID, AddStudentToCourseViewModel student)
{
// 1. Validation
var courseEntity = _db.Courses.FirstOrDefault(x => x.ID == ID);
if(courseEntity == null)
{
throw new CourseNotFoundException();
}
var studentEntity = _db.Persons.FirstOrDefault(x => x.SSN == student.SSN);
if (studentEntity == null)
{
throw new StudentNotFoundException();
}
// Checking to see if the course is full
int studentCount = _db.CourseRegistrations.Count(x => x.CourseID == ID && x.Active == true);
if (studentCount >= courseEntity.MaxStudents)
{
throw new CourseFullException();
}
// Checking to see if the student is already enrolled in the course.
var enrolled = _db.CourseRegistrations.FirstOrDefault(x => x.StudentID == studentEntity.ID && x.CourseID == ID);
if(enrolled != null)
{
if (enrolled.Active)
{
throw new StudentAlreadyEnrolledException();
}
}
// Checking to see if the student was on the waiting list
// If he was, we remove him from it.
var waiting = _db.CourseWaitingList.FirstOrDefault(x => x.StudentID == studentEntity.ID && x.CourseID == ID);
if(waiting != null)
{
_db.CourseWaitingList.Remove(waiting);
_db.SaveChanges();
}
// 2. Saving the registration
// If the student was already enrolled and simply not active
// We set his status to active.
if(enrolled != null)
{
enrolled.Active = true;
}
else
{
var courseRegistration = new CourseRegistration
{
CourseID = ID,
StudentID = studentEntity.ID,
Active = true
};
_db.CourseRegistrations.Add(courseRegistration);
_db.SaveChanges();
}
// 3. Building the return object
var studentDTO = new StudentDTO
{
ID = studentEntity.ID,
Name = studentEntity.Name,
SSN = studentEntity.SSN
};
return studentDTO;
}
/// <summary>
/// Adds the student to the course with the given ID
/// If no course/student is found, an Object not found exception is thrown.
/// </summary>
/// <param name="ID"></param>
/// <returns></returns>
public StudentDTO AddStudentToCourse(int ID, StudentViewModel student)
{
// 1. Validation
var courseEntity = _db.Courses.FirstOrDefault(x => x.ID == ID);
if(courseEntity == null)
{
throw new CourseNotFoundException();
}
var studentEntity = _db.Persons.FirstOrDefault(x => x.SSN == student.SSN);
if(studentEntity == null)
{
throw new StudentNotFoundException();
}
// 2. Saving the registration
var courseRegistration = new CourseRegistration
{
CourseID = ID,
StudentID = studentEntity.ID
};
_db.CourseRegistrations.Add(courseRegistration);
_db.SaveChanges();
// 3. Building the return object
var studentDTO = new StudentDTO
{
ID = studentEntity.ID,
Name = studentEntity.Name,
SSN = studentEntity.SSN
};
return studentDTO;
}
/// <summary>
/// Adds the student to the waiting list
/// of the course with the given ID
/// </summary>
/// <param name="ID"></param>
/// <param name="student"></param>
public StudentDTO AddStudentToWaitingList(int ID, AddStudentToCourseViewModel student)
{
// 1. Validation
var courseEntity = _db.Courses.FirstOrDefault(x => x.ID == ID);
if (courseEntity == null)
{
throw new CourseNotFoundException();
}
// Checking to see if the student exists
var studentEntity = _db.Persons.FirstOrDefault(x => x.SSN == student.SSN);
if (studentEntity == null)
{
throw new StudentNotFoundException();
}
// Checking to see if the student is already enrolled in the course.
var enrolled = _db.CourseRegistrations.FirstOrDefault(x => x.StudentID == studentEntity.ID && x.CourseID == ID);
if (enrolled != null)
{
if (enrolled.Active)
{
throw new StudentAlreadyEnrolledException();
}
}
// Checking to see if the student was already on the waiting list
var waiting = _db.CourseWaitingList.FirstOrDefault(x => x.StudentID == studentEntity.ID && x.CourseID == ID);
if (waiting != null)
{
throw new StudentAlreadyOnWaitingListException();
}
// 2. Saving the registration
var courseRegistration = new CourseWaitingListRegistration
{
CourseID = ID,
StudentID = studentEntity.ID
};
_db.CourseWaitingList.Add(courseRegistration);
_db.SaveChanges();
// 3. Building the return object
var studentDTO = new StudentDTO
{
ID = studentEntity.ID,
Name = studentEntity.Name,
SSN = studentEntity.SSN
};
return studentDTO;
}
