Making a temporary ID for entities in EF before saving - entity-framework

Question

If I have two tables, which have an Id, whish is an autogenerated int (seed), anyway I have a many to many relationship between these two tables which requires another table.
Now, I do a "dry run" to generate the items for the first two table before saving them, this works perfect. The problem is when I try to generate the items for the (many-many relationship) in the third table. Before saving the items all Ids in the first two tables will be set to 0, when adding items to the relation table I have no problems, the problems comes when saving the tables because the relationship table will have the Ids of 0.
Is there a way to overcome this problem? like assigning a temp value which will be automatically changed to the real Id in the relationship table before saving it ?

Answer 1

For the same reason, I've chosen not to use default Seed methods (AddOrUpdate) provided by EF, but I'm rather writing my own seed methods.
Now if I want to set up relationships, I'm not explicitly using ID's, but rather use navigational properties.
Imagine the scenario:
public class User
{
public int Id {get;set;}
public string Name {get;set;}
public virtual IList<Roles> Roles { get;set;}
}
public class Role
}
public int Id {get;set;}
public string Name {get;set;}
public virtual IList<User> Users {get;set;}
}
Doing this will seed both values for user and roles and relationships once you hit the save changes:
Role admin = new Role
{
Name = "Administrator"
};
Role basic = new Role
{
Name = "Basic"
};
User user = new User
{
Name = "John",
Roles = new List<Role>()
{
basic,
admin
}
}
db.Users.Add(user);
db.SaveChanges();