Linq Include not loading List

Question

I've been for a while trying to find out why the Include clause is not loading the related collection: I have two classes with a one-to-many relationship:

 public class AgencyNote : IAutId
    {
        [Key]
        public int aut_id { get; set; }
        public string Comment { get; set; }
        [DisplayName("Note Created Date")]
        public DateTime NoteDate { get; set; }
        [DisplayName("Contact Date")]
        public DateTime ContactDate { get; set; }
        [ForeignKey("tbl_agency")]        
        public int AgencyId { get; set; }
        [DisplayName("User")]
        public string RipsUser { get; set; }        
        public virtual ICollection<AgencyNoteAttachment> AgencyNoteAttachments { get; set; }
        public virtual tbl_agency tbl_agency { get; set; }
    }

and

 public class AgencyNoteAttachment
    {        
        [Key]
        public int aut_id { get; set; }
        public string Url { get; set; }
        public string FileName { get; set; }        
        public int AgencyNoteId { get; set; }
        [NotMapped]        
        [ForeignKey("AgencyNoteId")]
        public virtual AgencyNote AgencyNote { get; set; }        
    }

Context class:

public DbSet<AgencyNote> AgencyNotes { get; set; } 

public DbSet<AgencyNoteAttachment> AgencyNoteAttachments { get; set; }

This is the action where I'm using the Include clause:

private IQueryable<AgencyNote> GetNotes(int agencyId)
{                
  return _ctx.AgencyNotes
    .Include(a => a.tbl_agency)
    .Include(a => a.AgencyNoteAttachments)
    .OrderByDescending(f => f.NoteDate)
    .Where(x => x.AgencyId == agencyId);   
}

I'm getting AgencyNotesAttachments always null from this action even if I know it's not null, what's going on? Any question let me know...

My guess is relationship is not well created due to you are using NotMapped attribute. Remove it, at let us know what happen — ocuenca
– ocuenca, Commented Oct 31, 2016 at 15:26
@octavioccl I don't understand what happened, but before I had to use the NotMapped attribute otherwise EF would create an extra column in the table(something like the primary keys of both tables joined). If I didn't use NotMapped an error was raised because EF created that column, now I just removed and it works!!! — AlexGH
– AlexGH, Commented Oct 31, 2016 at 15:34
I'm going to create an answer explaining you why that happened — ocuenca
– ocuenca, Commented Oct 31, 2016 at 15:37

ocuenca · Accepted Answer · 2016-10-31 15:43:38Z

2

If you add just the navigation properties between the related entities, then EF will create the FK column for you in the AgencyNoteAttachment table. Now, EF by convention can interpret AgencyNoteId is the FK of that relationship, but is good idea do that explicitly as you already have in your model or using ForeignKey attribute on FK property:

public class AgencyNoteAttachment
{        
    [Key]
    public int aut_id { get; set; }
    public string Url { get; set; }
    public string FileName { get; set; } 

    [ForeignKey("AgencyNote")]       
    public int AgencyNoteId { get; set; }

    public virtual AgencyNote AgencyNote { get; set; }        
}

If you want to learn more about conventions, take a look this link

answered Oct 31, 2016 at 15:43

ocuenca

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