Entity FrameWork many-to-many - asp.net-mvc-3

Question

public class Project
{
public virtual int ID { get; set; }
[Required]
public virtual String Title { get; set; }
public String Definition { get; set; }
public DateTime StartDate { get; set; }
[Required]
public int CreaterID { get; set; }
public virtual ICollection<Status> Status { get; set; }
public virtual ICollection<Task> Tasks { get; set; }
public virtual ICollection<User> Users { get; set; }
public Project()
{
Users = new HashSet<User>();
}
}
public class User
{
public int ID { get; set; }
[DisplayName("Kullanıcı Adı")]
[Required]
[MinLength(5, ErrorMessage = "Kullanıcı Adı En Az 5 Karakter Olmalıdır")]
public string username { get; set; }
[DataType(DataType.Password)]
[DisplayName("Şifre")]
[Required]
[MinLength(3,ErrorMessage="Şifre En Az 3 Karakter Olmalıdır")]
public string password { get; set; }
[Required]
public String Name { get; set; }
[Required]
public String Surname { get; set; }
public int? CreaterID { get; set; }
public int level { get; set; }
public ICollection<Task> Tasks { get; set; }
public ICollection<Project> Projects { get; set; }
public User()
{
Projects = new HashSet<Project>();
}
}
public class TaskDB : DbContext
{
public DbSet<Comment> Comments { get; set; }
public DbSet<Project> Projects { get; set; }
public DbSet<Situation> Situaitons { get; set; }
public DbSet<Task> Tasks { get; set; }
public DbSet<User> Users { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Project>().
HasMany(c => c.Users).
WithMany(p => p.Projects).
Map(
m =>
{
m.MapLeftKey("ProjectId");
m.MapRightKey("UserId");
m.ToTable("ProjectUser");
});
}
}
If I add project , current user added to project users list but project not added current user's projects list
This is my project add code
[HttpPost]
public ActionResult Create(Project proje,Status status)
{
proje.StartDate = DateTime.Now;
proje.Status = new HashSet<Status>();
var user = _db.Users.Single(r=> r.ID == UserRole.ID);
proje.Users.Add(user);
proje.Status.Add(status);
user.Projects.Add(proje);
if (ModelState.IsValid)
{
var projeler = _db.Projects;
projeler.Add(proje);
_db.SaveChanges();
return RedirectToAction("Index");
}
return View(proje);
}
I Search this problem's cause I did not find , I want to learn why entity framework add user to project's list but not add project to user's list

Answer 1

Your code to add the new project to the database looks correct and the relationship is most likely stored.
But possibly you don't load the Projects list with a User. If you call...
var project = _db.Projects.Single(p => p.ID == 1);
var users = project.Users; // lazy loading because Users is virtual
...you will see the project's users because they get lazily loaded since the Project.Users property is marked as virtual. If you do the same with a User...
var user = _db.Users.Single(u => u.ID == 1);
var projects = user.Projects; // no lazy loading because Projects is not virtual
...the projects don't get loaded because the User.Projects property is not marked as virtual.
Either mark the property as virtual as well to enable lazy loading for the User.Projects collection:
public virtual ICollection<Project> Projects { get; set; }
Or use eager loading:
var user = _db.Users.Include(u => u.Projects).Single(u => u.ID == 1);