// GET: Instructor
public ActionResult Index(int? id, int? courseID)
{
var viewModel = new InstructorIndexData();
viewModel.Instructors = db.Instructors
.Include(i => i.OfficeAssignment)
.Include(i => i.Courses.Select(c => c.Department))
.OrderBy(i => i.LastName);
if (id != null)
{
ViewBag.InstructorID = id.Value;
viewModel.Courses = viewModel.Instructors.Where(
i => i.ID == id.Value).Single().Courses;
}
if (courseID != null)
{
ViewBag.CourseID = courseID.Value;
// Lazy loading
//viewModel.Enrollments = viewModel.Courses.Where(
// x => x.CourseID == courseID).Single().Enrollments;
// Explicit loading
var selectedCourse = viewModel.Courses.Where(x => x.CourseID == courseID).Single();
db.Entry(selectedCourse).Collection(x => x.Enrollments).Load();
foreach (Enrollment enrollment in selectedCourse.Enrollments)
{
db.Entry(enrollment).Reference(x => x.Student).Load();
}
viewModel.Enrollments = selectedCourse.Enrollments;
}
return View(viewModel);
}
//
// GET: /Instructor/
public ViewResult Index(Int32? id, Int32? courseID)
{
#region Eager Loading
//var viewModel = new InstructorIndexData();
//viewModel.Instructors = db.Instructors
// .Include(i => i.Courses.Select(c => c.Department))
// .OrderBy(i => i.LastName);
//if (null != id)
//{
// //Fetch the matching courses for the selected instructor.
// ViewBag.PersonID = id;
// viewModel.Courses = viewModel.Instructors.Where(i => i.PersonID == id.Value)
// .Single().Courses;
//}
//if (null != courseID)
//{
// //Fetchthe matching enrollments for the selected course.
// ViewBag.CourseID = courseID.Value;
// viewModel.Enrollments = viewModel.Courses.Where(c => c.CourseID == courseID)
// .Single().Enrollments;
//}
//return View(viewModel);
#endregion Eager Loading
#region Explicit Loading
var viewModel = new InstructorIndexData();
viewModel.Instructors = this._db.Instructors
.Include(i => i.Courses.Select(c => c.Department))
.OrderBy(i => i.LastName);
if (id != null)
{
ViewBag.PersonID = id.Value;
viewModel.Courses = viewModel.Instructors
.Where(i => i.PersonID == id.Value)
.Single()
.Courses;
}
if (null != courseID)
{
ViewBag.CourseID = courseID.Value;
var selectedCourse = viewModel.Courses
.Where(c => c.CourseID == courseID.Value)
.Single();
//Use the Collection method to explicitly load a collection of entities.
this._db.Entry(selectedCourse).Collection(x => x.Enrollments).Load();
foreach (var enrollment in selectedCourse.Enrollments)
{
//Use the Reference method to explicitly load an entity.
this._db.Entry(enrollment).Reference(x => x.Student).Load();
}
viewModel.Enrollments = selectedCourse.Enrollments;
}
return View(viewModel);
#endregion Explicit Loading
}
