When a user selects an item from dropdown list then that item must be removed for that user in mvc 4 - html

Question

I am creating a user course project for learning MVC 4. In this project, when a user logs in they can see their courses and other details. A user can create or edit the courses. So I am displaying list of courses in dropdown list during create and edit. What I want is, when a user selects a course and it is added to his list of courses then that course should not be displayed in the dropdown list for that user. Some code for create is given below:
CourseController:
public ActionResult Create()
{
User user = (User)Session["User"];
var usr = db.Users.Find(user.UserId);
if (Session["User"] != null)
{
ViewBag.CourseId = new SelectList(db.Courses, "CourseId", "CourseName");
ViewBag.UserId = usr.UserId;
ViewBag.FirstName = usr.FirstName;
}
return View();
}
//
// POST: /Course/Create
[HttpPost]
public ActionResult Create(UserCourse usercourse)
{
User user = (User)Session["User"];
var usr = db.Users.Find(user.UserId);
if (Session["User"] != null)
{
if (ModelState.IsValid)
{
db.UserCourses.Add(usercourse);
db.SaveChanges();
return RedirectToAction("Index");
}
ViewBag.CourseId = new SelectList(db.Courses, "CourseId", "CourseName", usercourse.CourseId);
ViewBag.UserId = usr.UserId;//from c in db.Users.Where(u => u.UserId == usercourse.UserId) select c;
ViewBag.FirstName = usr.FirstName;
return View();
}
return View(usercourse);
}
Create.cshtml:
<div class="editor-label">
#Html.DisplayNameFor(model => model.CourseId)
</div>
<div class="editor-field">
#Html.DropDownList("CourseId", String.Empty)
#Html.ValidationMessageFor(model => model.CourseId)
</div>
<p>
<input type="submit" value="Create" />
</p>
Model class for User:
public partial class User
{
public User()
{
this.UserCourses = new HashSet<UserCourse>();
}
public int UserId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
[Required(ErrorMessage = "Please Provide User Name", AllowEmptyStrings = false)]
public string UserName { get; set; }
[Required(ErrorMessage = "Please Provide Password", AllowEmptyStrings = false)]
[DataType(System.ComponentModel.DataAnnotations.DataType.Password)]
public string Password { get; set; }
public string Address { get; set; }
public string City { get; set; }
public string Email { get; set; }
public string PhoneNo { get; set; }
public virtual ICollection<UserCourse> UserCourses { get; set; }
}
Model class for Course:
public partial class Course
{
public Course()
{
this.UserCourses = new HashSet<UserCourse>();
}
public int CourseId { get; set; }
public string CourseName { get; set; }
public virtual ICollection<UserCourse> UserCourses { get; set; }
}
Model class for UserCourse:
public partial class UserCourse
{
public int Id { get; set; }
public Nullable<int> UserId { get; set; }
public Nullable<int> CourseId { get; set; }
public virtual Course Course { get; set; }
public virtual User User { get; set; }
}
Please reply.

Answer 1

[EDITED]: Try it this way:
public ActionResult Create()
{
User user = (User)Session["User"];
var usr = db.Users.Find(user.UserId);
if (Session["User"] != null)
{
var courses = db.Courses.Where(x=>!x.UserCourses.Any(y=>y.CourseId == x.CourseId && y.UserId == usr.UserId)).ToList();
ViewBag.CourseId = new SelectList(courses , "CourseId", "CourseName");
ViewBag.UserId = usr.UserId;
ViewBag.FirstName = usr.FirstName;
}
return View();
}
//
// POST: /Course/Create
[HttpPost]
public ActionResult Create(UserCourse usercourse)
{
User user = (User)Session["User"];
var usr = db.Users.Find(user.UserId);
if (Session["User"] != null)
{
if (ModelState.IsValid)
{
db.UserCourses.Add(usercourse);
db.SaveChanges();
return RedirectToAction("Index");
}
var courses = db.Courses.Where(x=>!x.UserCourses.Any(y=>y.CourseId == x.CourseId && y.UserId == usr.UserId)).ToList();
ViewBag.CourseId = new SelectList(courses, "CourseId", "CourseName", usercourse.CourseId);
ViewBag.UserId = usr.UserId;//from c in db.Users.Where(u => u.UserId == usercourse.UserId) select c;
ViewBag.FirstName = usr.FirstName;
return View();
}
return View(usercourse);
}