Entity Framework many to many relationship Delete - entity-framework

Question

I have a class that is called User. It has a property called Roles. Each user has many roles and each role can be assigned to many users.
The relationship is established by a 3rd table. I'd like to be able to remove a role from a User. However, I am calling the database twice. Once to fully load the "User" role and once to delte the role.
var user = this.Users.Include(f => f.Roles)
.SingleOrDefault(f => f.CustomerID == customerId && f.UserID == userId);
if (user != null)
{
var role = user.Roles.FirstOrDefault(f => f.RoleID == roleId);
if (role != null)
{
user.Roles.Remove(role);
return this.SaveChanges() > 0;
}
}
I tried doing this but it didn't work.
var user = new User { CustomerID = customerId, UserID = userId };
this.Users.Attach(user);
var role = new Role { RoleID = roleId };
this.Roles.Attach(role);
user.Roles.Add(role);
user.Roles.Remove(role);
return this.SaveChanges() > 0;
My Context has a DbSet<User> and DbSet<Role>. I don't have one for UserRole and I don't intend to have it.
Am i doing it right and do I need to always do 2 database calls?
-- User Class
[DataContract(Namespace = "urn:AES/Schemas/2014/09", IsReference = true)]
public class User
{
.....
[DataMember]
public List<Role> Roles { get; set; }
[DataMember]
public bool Active { get; set; }
}
The Mapping
this.HasMany(u => u.Roles)
.WithMany()
.Map(m =>
{
// The "left" key is the one specified in the HasMany method; the "right" key is the one specified in the WithMany method.
m.MapLeftKey(new string[] { "CustomerID", "UserID" });
m.MapRightKey("RoleID");
m.ToTable("UserRoles");
}
);
// Table & Column Mappings
this.ToTable("Users");
}

Answer 1

Curious why you don't model those other tables like UserRoles, are you just lazy? =)
But seriously, what you're doing is fine however for mass deletes EF doesn't have a bulk delete capability, you are better off simply executing the DELETE statement directly, like this:
using (System.Data.Common.DbCommand cmd = Context.Database.Connection.CreateCommand())
{
cmd.CommandText = #"DELETE FROM Table WHERE KeyColumn = #Id";
YourSqlHelper.AddParameter(cmd, "#Id", id);
cmd.ExecuteNonQuery();
}