EF 4 Feature CTP 4 - Associate Many to Many - entity-framework

Question

I am using EF 4 Feature CTP 4.
I have the following database schema:
[Users] 1-M [UserRoles] M-1 [Roles]
I have a User and Role class (both POCOs).
When I try to associate an existing role to a user, a new record is getting inserted in the Roles table, instead of only inserting a new record in UserRoles.
So say I have User 1 and want to Associate with Role 2. When I try to save, I end up with a new record in Roles named "Role 2" with a record in UserRoles to the newly created Role. From the code below I was expecting only a new record in UserRoles with the mapping between User and Role.
Here is my POCO classes, mapping and test.
POCO Classes:
public class User {
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public byte[] DataVersion { get; set; }
private List<Role> roles = new List<Role>();
public virtual IList<Role> Roles {
get {
return roles;
}
}
}
public class Role {
public int Id { get; set; }
public string Name { get; set; }
public List<User> Users { get; set; }
}
Mapping:
public class UserConfiguration : EntityConfiguration<Domain.User> {
public UserConfiguration() {
this.MapSingleType(user => new {
UserId = user.Id,
FirstName = user.FirstName,
LastName = user.LastName,
DataVersion = user.DataVersion
});
this.Property(u => u.DataVersion).IsConcurrencyToken().HasStoreType("timestamp").StoreGeneratedPattern = StoreGeneratedPattern.Computed;
//Users <--> Roles
this.HasMany(u => u.Roles).WithMany(r => r.Users)
.Map("UserRoles", (u, r) => new {
UserId = u.Id,
RoleId = r.Id
});
}
}
public class RoleConfiguration : EntityConfiguration<Domain.Role> {
public RoleConfiguration() {
this.MapSingleType(role => new {
RoleId = role.Id,
RoleName = role.Name
});
}
}
Test:
public void AssignRoleTest() {
var userId = 1;
User user;
var userRepo = new UsersRepository();
user = userRepo.GetUser(userId);
var roleRepo = new RolesRepository();
var roleId = 2;
var role = roleRepo.GetRole(roleId);
user.Roles.Add(role);
userRepo.SaveUser(user);
}
Code for Repository Save:
public void SaveUser(User user) {
if (user.Id > 0) {
dbContext.Users.Attach(user);
dbContext.MarkAsModified(user);
}
else {
dbContext.Users.Add(user);
}

Answer 1

Try to use context.DetectChanges() in your SaveUser method. It should work because you are using same context for both loading and saving entity graph.