Question

I have three related tables. Calendar 1…* CalendarUser *…1 User. When I have edited the CalendarUsers in the edit calendar view I then post the ViewModel back to the controller. Here is my controller code:

    [HttpPost]
    public ActionResult Edit(int id, CreateCalendarViewModel cvm)
    {
        long userId = long.Parse(User.Identity.Name);

        db.Calendars.Attach(cvm.CurrentCalendar);
        cvm.Users= DbExtensions.GetUserList(userId);

        if (ModelState.IsValid)
        {
            ////Remove the deselected users
            cvm.CurrentCalendar.CalendarUsers.Clear();

            //Get the names from the selected users
            var selectedUsers = from u in cvm.Users
                                where cvm.SelectedUsers.Contains(u.Key)
                                select new KeyValuePair<long, string>(long.Parse(u.Key), u.Value);

            foreach (var selectedUser in selectedUsers)
            {

                User user = db.Users.Find(selectedUser.Key);

                //If usr does not exist create a new
                if (user == null)
                {
                    db.Users.Add(new User
                    {
                        UserId = selectedUser.Key,
                        Name = selectedUser.Value,
                        Expires = DateTime.Now,
                        AccessToken = string.Empty
                    });
                }

                //Add the binding to the calendar
                cvm.CurrentCalendar.CalendarUsers.Add(new CalendarUser
                {
                    CalendarId = cvm.CurrentCalendar.CalendarId,
                    UserId = selectedUser.Key
                });
            }

            db.Entry(cvm.CurrentCalendar).State = EntityState.Modified;

            db.SaveChanges();

        }

        return View(cvm);
    }

Here are my classes:

public partial class Calendar 
{ 
    public Calendar() 
    { 
        this.CalendarUsers = new HashSet<CalendarUser>(); 
    } 

    public int CalendarId { get; set; } 
    public string CalendarTitle { get; set; } 
    public string CalendarDescription { get; set; } 
    public long UserId { get; set; } 

    public virtual User User { get; set; } 
    public virtual ICollection<CalendarUser> CalendarUsers { get; set; } 
} 

public partial class CalendarUser 
{ 
    public int CalendarUserId { get; set; } 
    public int CalendarId { get; set; } 
    public long UserId { get; set; } 
    public Nullable<bool> IsAdmin { get; set; } 

    public virtual Calendar Calendar { get; set; } 
    public virtual User User { get; set; } 
} 

public partial class User 
{ 
   public User() 
   { 
       this.Calendars = new HashSet<Calendar>(); 
       this.CalendarUsers = new HashSet<CalendarUser>(); 
   } 

   public long UserId { get; set; } 
   public string Name { get; set; } 

   public virtual ICollection<Calendar> Calendars { get; set; } 
   public virtual ICollection<CalendarUser> CalendarUsers { get; set; } 
} 

For some reason when i save the changes the calendar is being deleted as well? I’ve searched a bit but noone seem to have the same problem? Am I doing it wrong? Is there a better way to update/remove related entities?

Answer 1

It seems that I forgot to include a hidden field in in the view containing the id of the user and the result was that when I updated the calendar it saved with Id = 0 and thus hid the objects in the view for the specified user. Mental note: Always verify in the database what is really happening.

I also need to look into whats happening when I send objects back and forth between views and controller. Sometimes it seems to manage by itself and sometimes I need to specify all the fields myself.