Lazy loading does not work in entity framework 5

Question

I have defined a (poco?) class in my domain project:

public class Club
{
   public Club()
   {
      ContactPersons = new HashSet<ContactPerson>();
   }

   public int Id { get; set; }

   [Required]
   [StringLength(64)]
   public string Name { get; set; }

   public virtual ICollection<ContactPerson> ContactPersons { get; set; }
}

public class ContactPerson
{
     public virtual int Id { get; set; }

     [StringLength(64)]
     public virtual string FirstName { get; set; }

     [StringLength(64)]
     public virtual string LastName { get; set; }
 }

In my MVC project I have my clubcontroller:

   public ActionResult Create(CreateClubViewModel model)
   {
      Club club = new Club();
      model.Initialize(club);
      IClubDb clubDb = DependencyResolverHelper.IClubDbService;
      clubDb.Create(club);  // create club in db
   }

    public ActionResult Display(string domain)
    {
        try
        {
            IClubDb clubDb = DependencyResolverHelper.IClubDbService;
            Club club = clubDb.Get(domain);
            return View(club);
        }
        catch (Exception)  // user is not logged iin
        {
            return View();
        }
    }

Finally, in my DB project I create and retrieve the club,

public Club Get(string name)
{
   return DataContext.Clubs
   //.Include(x => x.ContactPersons)
   .Single(r => r.Name == name);
}

 public int Create(Club club)
 {
         DataContext.Clubs.Add(club);
         return DataContext.SaveChanges();
 }

I have tried everything to get EF to lazy load the ContactPersons of my club object when I call the Get club in the Display method but ContactPersons has always a length of zero. However, if I eager load contact persons using the .include (I have commented this part out), then obviously ContactPersons contains a number of contacts.

I am not sure what I am doing wrong:

I have followed the guidelines for defining poco classes: http://msdn.microsoft.com/en-us/library/dd468057.aspx
I have a public parameter less constructor (but not protected constructor)
I have lazyloading enabled

I think I am missing a concept, the poco club class is also my domain entity which I insert into DB. What am I doing wrong? Whay I can't get lazy loading to work?

Try using a List<ContactPerson> instead of an ICollection<ContactPerson>. I don't think EF is clever enough to use ICollection's — Dominic Zukiewicz
– Dominic Zukiewicz, Commented Jan 1, 2013 at 21:38
Dominic, just tried your suggestion, still the same, ContactPersons is empty :( — user1780105
– user1780105, Commented Jan 1, 2013 at 22:14
@Dominic: ICollection<T> works quite fine. It even makes more sense since a List implies an order, and related entities are not returned in any particular order. — Matti Virkkunen
– Matti Virkkunen, Commented Jan 1, 2013 at 22:16
Yes Jayantha, I have these two lines when I intialize the db context: this.Configuration.LazyLoadingEnabled = true; this.Configuration.ProxyCreationEnabled = true; — user1780105
– user1780105, Commented Jan 2, 2013 at 20:09

Community · Accepted Answer · 2017-05-23 11:53:55Z

1

try ContactPersons.ToList();

this will force all entities to be loaded. see Entity framework, when call ToList() it will load FK objects automatically?

edited May 23, 2017 at 11:53

CommunityBot

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answered Aug 20, 2013 at 19:22

Bassam Alugili

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Comments

Kirill Bestemyanov · Accepted Answer · 2013-01-01 21:59:51Z

0

It seems that your LazyLoading performs when your dbContext is closed. So it will not load. You use ContactPerson in view, am i right?

answered Jan 1, 2013 at 21:59

Kirill Bestemyanov

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2 Comments

user1780105 Over a year ago

Yes, I access the club in View(club) of Display method. But I did try to access the contact person before the line "return view (club") and it was the same. I also tried to access the contact person when I get the club within DB project and it was not loaded.

user1780105 Over a year ago

When I use the debugger, the type of ContactPerson is not changed. I remember vaguely that EF creates a new type and inserts a hook in the getter accessor function. It appears that EF is not creating proxy objects at all, hence lazy loading fails. I have the following lines in my code: this.Configuration.LazyLoadingEnabled = true; this.Configuration.ProxyCreationEnabled = true;

wmasm · Accepted Answer · 2013-02-20 19:02:29Z

0

Did you forget to include the foreign key in your entity?

public class ContactPerson
{
    public virtual int Id { get; set; }

    [StringLength(64)]
    public virtual string FirstName { get; set; }

    [StringLength(64)]
    public virtual string LastName { get; set; }

    public int ClubId { get; set; }
    [ForeignKey("ClubId")]
    public virtual Club Club { get; set; } // if you need
}

answered Feb 20, 2013 at 19:02

wmasm

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