private void detach_Waitlists(Waitlist entity)
{
this.SendPropertyChanging();
entity.Course = null;
}
private void attach_Waitlists(Waitlist entity)
{
this.SendPropertyChanging();
entity.Course = this;
}
partial void DeleteWaitlist(Waitlist instance);
partial void UpdateWaitlist(Waitlist instance);
partial void InsertWaitlist(Waitlist instance);
//Get the selected student and course
//Try to enroll the student in the course
//If the course is full, put students on waitlist
private void enrollButton_Click(object sender, EventArgs e)
{
if (this.studentsLB.SelectedItem == null)
{
MessageBox.Show("Select a student to enroll.");
return;
}
Student student = getSelectedStudent();
//MessageBox.Show(student.ToString());
if (this.coursesLB.SelectedItem == null)
{
MessageBox.Show("Select a course to enroll in.");
return;
}
Course course = getSelectedCourse();
//MessageBox.Show(course.ToString());
string msg = null;
using (var db = new CoursemoDataContext())
{
var TxOptions = new System.Transactions.TransactionOptions();
TxOptions.IsolationLevel = System.Transactions.IsolationLevel.Serializable;
using (var Tx = new System.Transactions.TransactionScope(
System.Transactions.TransactionScopeOption.Required, TxOptions))
{
try {
if (delay_flag)
{
Delay();
}
var enrolled = from r in db.Registrations
where r.Netid == student.netid
where r.CRN == course.crn
select r;
if (delay_flag)
{
Delay();
}
var waiting = from w in db.Waitlists
where w.Netid == student.netid
where w.CRN == course.crn
select w;
//Is the student already enrolled in this class?
if (enrolled.Any())
{
//MessageBox.Show(student.netid + " is already enrolled in course " + course.crn);
msg = student.netid + " is already enrolled in course " + course.crn;
}
//Is the student on the waitlist for this class?
else if (waiting.Any())
{
//MessageBox.Show(student.netid + " is already on the waitlist for course " + course.crn);
msg = student.netid + " is already on the waitlist for course " + course.crn;
}
//Student not enrolled or waiting for this course
else
{
//Get number of registrations for this course
if (delay_flag)
{
Delay();
}
var query = (from r in db.Registrations
where r.CRN == course.crn
select r.RID).ToList();
//Is this class full?
if (query.Count == course.capacity)
{
//MessageBox.Show(course.crn + " is full, putting " + student.netid + " on the waitlist for this course.");
//Put on waitlist
if (delay_flag)
{
Delay();
}
Waitlist wait = new Waitlist
{
Netid = student.netid,
CRN = course.crn,
RegTime = DateTime.Now
};
db.Waitlists.InsertOnSubmit(wait);
if (delay_flag)
{
Delay();
}
var placeInLine = from w in db.Waitlists
where w.CRN == course.crn
orderby w.RegTime
select w.WID;
//MessageBox.Show(student.netid + " put on waitlist for " + course.crn + ". Place in line: " + (placeInLine.Count() + 1).ToString());
msg = student.netid + " put on waitlist for " + course.crn + ". Place in line: " + (placeInLine.Count() + 1).ToString();
}
else
{
//Enroll
if (delay_flag)
{
Delay();
}
Registration r = new Registration
{
Netid = student.netid,
CRN = course.crn
};
db.Registrations.InsertOnSubmit(r);
//MessageBox.Show(student.netid + " enrolled in " + course.crn);
msg = student.netid + " enrolled in " + course.crn;
}
}
db.SubmitChanges();
Tx.Complete();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
//msg = "Enrollment failed. Try again.";
//Tx.Dispose();
}
}
MessageBox.Show(msg);
}
}
