Entity Framework code first - Array of foreign keys

Question

I have an entity with a list of other entites.
The other entities are "read only" and are only a mere association.
The meaning is that the entity should only have a list of the other entities ids and nothing more.
How can I achive this so I can have as simple as possible update graph later on?

 public class Worker
 {
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int ID { get; set; }

    public string Name { get; set; }

    public double Age { get; set; }

    public int? ManagerID { get; set; }

    [ForeignKey("ManagerID")]
    public virtual Worker Manager { get; set; }

    /// <summary>
    /// This is just an association to the tasks. 
    /// An update graph should ignore the entity itself since 
    /// the task is immutable in this context!!!
    /// </summary>
    public virtual ICollection<Task> AssignedTasks { get; set; }
}

public class Task
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int ID { get; set; }

    public string TaskName { get; set; }

    public DateTime StartDate { get; set; }
    public DateTime EndDate { get; set; }

    /// <summary>
    /// This is just an association to the workers. 
    /// An update graph should ignore the entity itself 
    /// since the worker is immutable in this context!!!
    /// </summary>
    public virtual ICollection<Worker> AssignedWorkers { get; set; }
}

I need just the entities ids ... BUT the collections are used to build the DB schema...

In the example above - On update the worker just need to update the tasks ids that were assigned to him and not their whole data

Answer 1

You can mark the actual list of entities as private virtual. This will prevent outside access. Then create the list of ids as a property that does a .Select(e => e.Id) on your entity list. The entity list would only be able to be modified from inside the parent entity.