/// <summary>
/// Adds a student to the waiting list of a course.
/// </summary>
/// <exception cref="AppObjectNotFoundException">Thrown if the course is not found.</exception>
/// <exception cref="DuplicateCourseRegistrationException">Thrown if the student is already enrolled to the course or to the waiting list.</exception>
/// <param name="courseID">ID of the course.</param>
/// <param name="studentID">ID of the student.</param>
public void AddStudentToWaitingList(int courseID, StudentViewModel student)
{
//Check if course exists
Course course = _context.Courses.SingleOrDefault(c => c.ID == courseID);
if (course == null)
{
throw new AppObjectNotFoundException();
}
int studentID = _context.Students.Where(s => s.SSN == student.SSN).Select(s => s.ID).SingleOrDefault();
if (studentID == 0)
{
throw new AppObjectNotFoundException();
}
//Check to see if the user is already on the waiting list (or registered)
StudentEnrollment enrollment = _context.StudentEnrollment.SingleOrDefault(se => se.StudentID == studentID && se.CourseID == courseID && se.IsDeleted == false);
if (enrollment != null)
{
throw new DuplicateCourseRegistrationException();
}
//Check if the user was deleted before from the course.. if so, we undelete him and put ont he waitin glist
enrollment = _context.StudentEnrollment.SingleOrDefault(se => se.StudentID == studentID && se.CourseID == courseID && se.IsDeleted == true);
if (enrollment != null)
{
enrollment.IsDeleted = false;
enrollment.IsOnWaitingList = true;
}
else
{
enrollment = new StudentEnrollment
{
CourseID = courseID,
StudentID = studentID,
IsOnWaitingList = true,
};
_context.StudentEnrollment.Add(enrollment);
}
_context.SaveChanges();
}
/// <summary>
/// Adds a student to a course. If the student doesn't exist, it is created.
/// </summary>
/// <param name="courseID">The ID of the course.</param>
/// <param name="studentVM">The student VM.</param>
/// <returns>True if successful, false if the course does not exist.</returns>
public bool AddStudentToCourse(int courseID, StudentViewModel studentVM)
{
//Does the course exist?
Course course = _context.Courses.Where(c => c.ID == courseID).SingleOrDefault();
if (course == null)
{
return false;
}
Student student = _context.Students.Where(s => s.SSN == studentVM.SSN).SingleOrDefault();
if (student == null)
{
student = new Student { Name = studentVM.Name, SSN = studentVM.SSN };
_context.Students.Add(student);
_context.SaveChanges();
}
StudentEnrollment studentEnrollment = new StudentEnrollment { StudentID = student.ID, CourseID = courseID };
_context.StudentEnrollment.Add(studentEnrollment);
_context.SaveChanges();
return true;
}
/// <summary>
/// Adds a student to a course. Assumes the student already exists.
/// Will not allow more than MaxStudents students.
/// </summary>
/// <exception cref="AppObjectNotFoundException">Thrown if either the course or the student doesn't exist.</exception>
/// <param name="courseID">The ID of the course.</param>
/// <param name="SSN">The SSN of the student.</param>
/// <returns>A student object.</returns>
public StudentDTO AddStudentToCourse(int courseID, string SSN)
{
//Does the course exist?
Course course = _context.Courses.Where(c => c.ID == courseID).SingleOrDefault();
if (course == null)
{
throw new AppObjectNotFoundException();
}
Student student = _context.Students.Where(s => s.SSN == SSN).SingleOrDefault();
if (student == null)
{
throw new AppObjectNotFoundException();
}
//Verify that we won't violate the MaxStudents property
int numStudents = _context.StudentEnrollment.Count(se => se.CourseID == courseID && se.IsDeleted == false && se.IsOnWaitingList == false);
if (numStudents == course.MaxStudents)
{
throw new FullCourseException();
}
StudentEnrollment studentEnrollment = new StudentEnrollment { StudentID = student.ID, CourseID = courseID, IsOnWaitingList = false, IsDeleted = false };
//Verify that the user isn't already registered..
if (_context.StudentEnrollment.SingleOrDefault(se => se.StudentID == student.ID && se.CourseID == courseID && se.IsDeleted == false && se.IsOnWaitingList == false) != null)
{
throw new DuplicateCourseRegistrationException();
}
//If the user is already on a waiting list, we remove it from the waiting list..
StudentEnrollment enrollment = _context.StudentEnrollment.SingleOrDefault(se => se.StudentID == student.ID && se.CourseID == courseID && se.IsOnWaitingList == true);
if (!(enrollment == null))
{
_context.StudentEnrollment.Remove(enrollment);
}
//If the user has already registered on the course but the enrollment has been deleted.. we simply "undelete" it..
enrollment = _context.StudentEnrollment.SingleOrDefault(se => se.CourseID == courseID && se.StudentID == student.ID && se.IsDeleted == true);
if (enrollment != null)
{
enrollment.IsDeleted = false;
}
else
{
_context.StudentEnrollment.Add(studentEnrollment);
}
_context.SaveChanges();
return new StudentDTO { ID = student.ID, Name = student.Name, SSN = student.SSN };
}