示例#1
0
        /// <summary>
        /// Method that adds a student to a course with a given ID.
        /// The attributes needed to add a student to a course are given with 
        /// a view model class.
        /// </summary>
        /// <param name="id">ID of the course</param>
        /// <param name="model">Add student view model (ViewModel class)</param>
        /// <returns>The student that was added to the course (DTO class)</returns>
        public StudentDTO AddStudentToCourse(int id, AddStudentViewModel model)
        {
            var course = _db.Courses.SingleOrDefault(x => x.ID == id);
            var student = _db.Students.SingleOrDefault(x => x.SSN == model.SSN);
            if (course == null || student == null)
            {
                throw new AppObjectNotFoundException();
            }

            var studentInCourse = _db.CourseStudents.SingleOrDefault(x => x.CourseID == id && x.StudentID == student.ID && x.IsActive == true);
            if(studentInCourse != null)
            {
                throw new AppObjectIllegalAddException();
            }

            if (course.MaxStudents <= GetStudentsInCourse(id).Count)
            {
                throw new AppMaxReachedException();
            }

            var studentInWaitingList = _db.WaitingLists.SingleOrDefault(x => x.CourseID == id && x.StudentID == student.ID);
            if(studentInWaitingList != null)
            {
                _db.WaitingLists.Remove(studentInWaitingList);
            }

            var courseStudent = _db.CourseStudents.SingleOrDefault(x => x.CourseID == id && x.StudentID == student.ID && x.IsActive == false);

            if(courseStudent != null)
            {
                courseStudent.IsActive = true;
            }
            else
            {
                var newCourseStudent = new CourseStudent
                {
                    CourseID = course.ID,
                    StudentID = student.ID,
                    IsActive = true
                };
                _db.CourseStudents.Add(newCourseStudent);
            }

            _db.SaveChanges();

            var result = new StudentDTO
            {
                Name = student.Name,
                SSN = student.SSN
            };

            return result;
        }
        /// <summary>
        /// Adds a student to a given course
        /// </summary>
        /// <param name="id"></param>
        /// <param name="model"></param>
        /// <returns></returns>
        public StudentDTO AddStudentToCourse(int id, AddStudentViewModel model)
        {
            
            var course = _db.Courses.SingleOrDefault(x => x.ID == id);
            //if course doesn't exist an error will be thrown. Not possible to add student to non existing courses
            if (course == null)
            {
                throw new AppObjectNotFoundException();
            }

            //verify that the person exists!
            var person = _db.Persons.SingleOrDefault(x => x.SSN == model.SSN);
            if(person == null)
            {
                throw new AppObjectNotFoundException();
            }

            //count students in the course
            var countStudents = _db.CourseStudents.Count(x => x.CourseID == course.ID);

            //stop adding new students if course is full
            if(countStudents >= course.MaxStudents)
            {
                throw new MaxStudentException();
            }

            //check if student already in course
            var studentAlreadyInCourse = (from cs in _db.CourseStudents
                                         where cs.CourseID == id
                                         && person.ID == cs.PersonID
                                         select cs).SingleOrDefault();

            if (studentAlreadyInCourse != null)
            {
                throw new DuplicateEntryException();
            }


            //check if person is on the waitinglist
            var isOnWaitList = (from cwl in _db.CourseWaitingList
                                //join p in _db.Persons on cwl.PersonID equals p.ID
                                where cwl.CourseID == id
                                && person.ID == cwl.PersonID
                                select cwl).SingleOrDefault();   

            //person is on the waitinglist
            if(isOnWaitList != null)
            {
                _db.CourseWaitingList.Remove(isOnWaitList);
                _db.SaveChanges();
            }

            //Actually add the record
            var courseStudent = new CourseStudent
            {
                PersonID = person.ID,
                CourseID = course.ID
            };

            _db.CourseStudents.Add(courseStudent);
            _db.SaveChanges();

            //3.Figure out what to return.
            var returnValue = new StudentDTO
            {
                Name = person.Name,
                SSN = person.SSN
            };
            return returnValue;
        }