Entity Framework 6 One-To-Many Relationship without Navigation Property

Question

I have 2 table: A and B with one-to-many relationship, these table were implemented in EF 6 as below:

public class A
{
    [Key]
    public int AID {get;set;}
    public string AName {get;set;}
}

public class B
{
    [Key]
    public int BID {get;set;}
    public string BName {get;set;}
    public int AID {get;set;}

    [ForeignKey("AID")]
    public A InstanceOfClassA {get;set;}
}

PROBLEM

When I retrieve B from context, InstanceOfClassA always null.

Assumption

Because there's no navigation property refer to B in A entity, therefore, entity framework doesn't lazy load A when retrieve B.

Expecting

Because I don't need to access B from A, therefore I want to get rid of navigation property in A but still preserve the ability of lazy load A from B.

NOTE

I saw a post from Map Many to Many relationship without navigation property but this doesn't suit in my case.

Is there anyway that I can force to lazy load A from B without using explicit include var b = context.B.Include(x => x.InstanceOfClassA);? Maybe Custom Convention

EDIT 1

I tried using convention as follow and still get no luck:

modelbuilder.Entity<B>()
    .HasRequired<A>(x => x.InstanceOfClassA);

If you're going down vote my question, please take some time to leave a comment on what I did wrong. — Doan Cuong, Mar 07 '14 at 02:49
I don't see anything wrong with this question. I spent a bit of time researching the same thing so that I wouldn't have to Include() on everything I was sending from a Service. I think I ended up creating a constructor in a partial class that loaded nav properties. Dunno if that works for you. — Chad McGrath, Mar 07 '14 at 04:06
I though about manually loaded dependency too. But still looking for a solution that can be re used in future project. Custom Convention for example, but I go no idea on how to implement custom convention for this kind of relationship — Doan Cuong, Mar 07 '14 at 04:13

score 2 · Accepted Answer · answered Mar 07 '14 at 05:27

2

To get lazy loading working, you have to mark navigation property with virtual keyword:

[ForeignKey("AID")]
public virtual A InstanceOfClassA {get;set;}

answered Mar 07 '14 at 05:27

MarcinJuraszek

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Work like a charm! I was mixing up eager loading and lazy loading – Doan Cuong Mar 07 '14 at 05:29
Is this specifically just for the difference between lazy loading and eager? `virtual` seems necessary to get it to work at all – Don Cheadle Dec 14 '15 at 15:52

Entity Framework 6 One-To-Many Relationship without Navigation Property

1 Answers1