ASP.Net MVC3 EF 4.1 Model Code First Parent ID construct

Question

i have these classes:

public class Event
{
  [Key]
  public int ID { get; set; }

  [Required]
  public string Name { get; set; }

  [Required]
  public DateTime Begin { get; set; }

  [Required]
  public DateTime End { get; set; }

  public string Description { get; set; }

  public virtual ICollection<EventRegistration> Registrations { get; set; }

  public virtual ICollection<EventComment> Comments { get; set; }
}

public class EventComment
{
    [Key]
    public int ID { get; set; }

    [Required]
    public int PersonID { get; set; }

    [Required]
    public int EventID { get; set; }

    [Required]
    public DateTime EntryDate { get; set; }

    [Required]
    public string Comment { get; set; }

    public int? ParentCommentID { get; set; }

    public virtual Event CommentEvent { get; set; }

    public virtual Person CommentPerson { get; set; }

    public virtual EventComment ParentComment { get; set; }

    public virtual ICollection<EventComment> ChildComments { get; set; }

}

In the context i have the following:

protected override void OnModelCreating(DbModelBuilder modelBuilder) 
 { 
     modelBuilder.Conventions.Remove<PluralizingTableNameConvention>(); 
     modelBuilder.Entity<EventComment>()
                 .HasMany(s => s.ChildComments)
                 .WithOptional()
                 .HasForeignKey(s => s.ParentCommentID);
 } 

The EventComments and children get loaded correctly. But every Event loads all EventComments with that EventID. The Event class should only load EventComments with no ParentID. How can i do that?

Answer 1

If I understand correctly, you're doing something like

var event = (from e in ctx.Event.Include(p=>p.EventComment) select e);

and you don't want all of the EventComments loaded, just specific ones.

Unfortunately EF does not provide a mechanism to filter the .Include.

You can however use projections as outlined here:

https://stackoverflow.com/a/5666403/141172