ef core ignore navigation property

Question

I have an entity User that has two properties CreatedBy and UpdatedBy both referencing User. By default, EF assumes that these two as a one to one relation to each other. I get the following error message:

Message: System.InvalidOperationException : The child/dependent side could not be determined for the one-to-one relationship that was detected between 'User.CreatedBy' and 'User.UpdatedBy'. To identify the child/dependent side of the relationship, configure the foreign key property. If these navigations should not be part of the same relationship configure them without specifying the inverse. See http://go.microsoft.com/fwlink/?LinkId=724062 for more details.

Currently, I have a class like this:

public class User
{

    public int Id { get; set; }

    public int? CreatedById { get; set; }
    public User CreatedBy { get; set; }

    public int? UpdatedById { get; set; }
    public User UpdatedBy { get; set; }

}

Basically, here is what I am trying:

The created and updated would have no relation to each other (no navigation/inverse property needed)
Any number of users can have the same CreatedBy and any number of users can have the same UpdatedBy.

How can I ask EF to just ignore the navigation property? The main reason I have CreatedBy is so I can use Include(u => u.CreatedBy) later on. I know using IEnumerable<User> AllCreatedUsers property would solve this but I did not want to create an IEnumerable for each in my entity. Is there any way to do this with fluent API?

Here is what I tried:

modelBuilder.Entity<User>()
                .Property<IEnumerable<User>>("AllCreatedUsers");

modelBuilder.Entity<User>().HasOne(u => u.CreatedBy)
                                .WithMany(u => EF.Property<IEnumerable<User>>(u, "AllCreatedUsers"));

try using `ForeignKey` data annotation on `UpdatedBy` and `CreatedBy` — Vivek Nuna, May 12 '18 at 07:05
Why do you want EF to ignore a navigation property when you add it so you have a navigation property for EF? — Progman, May 12 '18 at 07:06
@viveknuna yeah.. i had tried the `ForeignKey` in annotations and fluent API — Neville Nazerane, May 12 '18 at 07:34
@Progman Considering I would never use such an `IEnumerable`, there is no point in having so many unused properties in a class. — Neville Nazerane, May 12 '18 at 07:42
@viveknuna yep. tried again `ForeignKey` worked. Last time I may have used fk for only one property. using it for both worked. — Neville Nazerane, May 12 '18 at 16:59

score 5 · Answer 1 · answered May 12 '18 at 09:03

5

You need to configure two Single Navigation Property relationships by using parameterless WithMany method overload:

modelBuilder.Entity<User>()
    .HasOne(u => u.CreatedBy)
    .WithMany();

modelBuilder.Entity<User>()
    .HasOne(u => u.UpdatedBy)
    .WithMany();

answered May 12 '18 at 09:03

Ivan Stoev

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I had tried this earlier. I even tried it with copy-pasting your code. It's still the same result – Neville Nazerane May 12 '18 at 16:48
All I can say is that this is the way to deal with such model. If you create a clean new project, copy/paste the `User` class from the question and the fluent configuration from the answer, you will see that it works. – Ivan Stoev May 12 '18 at 16:56
Yep, just tested, it worked fine on a clean project. However, there might be some special case(s) this doesn't consider. @vivek's code seems to work in both cases though. – Neville Nazerane May 12 '18 at 17:30
This doesn't make any sense to me. FKs are really unrelated to the issue (I could have included them in the fluent setup if they were not matching the convention), and data annotations are absolutely unnecessary (I would say obsolete) in EF Core. – Ivan Stoev May 12 '18 at 17:50

score 3 · Accepted Answer · answered May 12 '18 at 17:10

You ForeignKey data annotation for both the properties.

public class User
{
    public int Id { get; set; }

    public int? CreatedById { get; set; }
    [ForeignKey("CreatedById")]
    public User CreatedBy { get; set; }

    public int? UpdatedById { get; set; }
    [ForeignKey("UpdatedById")]
    public User UpdatedBy { get; set; }
}

ef core ignore navigation property

2 Answers2