mvc entity framework many to many user and role insert

问题

I have an mvc project with database first entityframework. In Project I have 3 tables.

Users >>> UsersInRoles <<< Roles with many to many relationship.

and my CreateUser codes below;

public bool CreateUser(string email, string password, string birthday,string firstname,string lastname)
    {
        bool result;
        var dogumgunu = Convert.ToDateTime(birthday);
        var sifre = FormsAuthentication.HashPasswordForStoringInConfigFile(password, "sha1");
        var confirmation = CreateConfirmationToken(email);
            try
            {
                var user = new User
                {
                    UserName = email,
                    Password = sifre,
                    UserJoinDate = DateTime.Now,
                    UserBirthDay = dogumgunu,
                    UserConfirmationToken = confirmation,
                    UserID = Guid.NewGuid(),
                    MemberFirstName = firstname,
                    MemberLastName = lastname
                };
                var role = new Role
                {
                    RoleName = "Client"
                };
                user.Roles.Add(role); //problem is here!!!!!!!!!
                _bb.Users.AddObject(user);
                _bb.SaveChanges();
                result = true;
            }
            catch (Exception)
            {

                result = false;
            }


        return result;
    }

In this code I am new user creating. And I am adding a role. But This code include a new Role in Roles table. I dont want to this. I want to just add UsersInRoles table a new user. What is wrong? Thanks for reply.

回答1:

Swap these two lines:

_bb.Users.AddObject(user);
user.Roles.Add(role);

because AddObject converts the whole object graph to the Added state. If you add the role afterwards, its state will remain Unchanged.

And you should fetch the role from the database first or create a Role object that only has an existing RoleId. (A so called stub entity).

So in stead of new Role you could do

var role = _bb.Roles.Single(r => r.RoleName == "Client");

来源：https://stackoverflow.com/questions/16786945/mvc-entity-framework-many-to-many-user-and-role-insert