EFCore Many/One to Many relationship of the same entity

Question

I am trying to set up a realationship between an object and versions of the same object. I am using EFCore and its saving the ID from one of the objects into both fields.

My objects are as follows:

public class Workflow
{
    public int WorkflowId { get; set; }

    [ForeignKey("Parent")]
    public int? ParentId { get; set; }
    public virtual Workflow Parent { get; set; }

    public virtual List<Workflow> Workflows { get; set; } = new List<Workflow>();

    public int InternalSequence { get; set; }

    public decimal Quantity { get; set; }

    public virtual List<WorkflowVersionLink> VersionLinks { get; set; } = new List<WorkflowVersionLink>();
}



public class WorkflowVersionLink
{
    public int WorkflowVersionLinkId { get; set; }

    public int? IsVersionOfId { get; set; }
    public virtual Workflow IsVersionOf { get; set; }

    public int? VersionId { get; set; }
    public virtual Workflow Version { get; set; }

    public bool IsLive { get; set; }
}

And I am setting up the OnModelCreating as follows:

//All of my attempts have used this:
modelBuilder.Entity<WorkflowVersionLink>()
.HasKey(t => new { t.IsVersionOfId, t.VersionId });



//Attempt one: No manual configuration



//Attempt two:
modelBuilder.Entity<WorkflowVersionLink>()
  .HasOne(lk => lk.Version)
  .WithMany(wf => wf.VersionLinks)
  .HasForeignKey(lk => lk.VersionId);



//Attempt three (following info from SO):
modelBuilder.Entity<WorkflowVersionLink>()
  .HasOne(lk => lk.IsVersionOf)
  .WithMany()
  .HasForeignKey(lk => lk.IsVersionOfId)
  .OnDelete(DeleteBehavior.Restrict);

modelBuilder.Entity<WorkflowVersionLink>()
  .HasOne(lk => lk.Version)
  .WithMany(wf => wf.VersionLinks)
  .HasForeignKey(lk => lk.VersionId);

I have already tried the approach here: Many-to-many self referencing relationship & the other approaches mentioned above.

I am open to changing to structure, before all of this I didn't use the WorkflowVersionLink Object, and just had a List Versions, however this failed also because I already have a list of child workflows (which I need to keep)

As you can see, I have attempted to fix this issue myself, but I am now stuck and decided to turn to StackOverflow.

You can see the database result here: (I am 100% sure I added two brand new objects that didnt have IDs each time I ran the code) database result

What am I doing wrong here?

Thanks

Did you try to use `WorkflowVersionLinkId` as the key and just add a Unique constraint on the `t.IsVersionOfId, t.VersionId` — Richard Hubley, Aug 28 '18 at 23:24
I'm Assuming the link to the WorkflowVersionLink object is the issue. — Richard Hubley, Aug 28 '18 at 23:24
if you are using no standard POCO Id should specific it with builder.Entity().HasKey(x => x.[keyproperty]); — Carlos Cocom, Aug 28 '18 at 23:29
*I have attempted to fix this issue myself* -- But, what's the issue? You should show the code that contains "the issue" and explain where/why it goes wrong. Also, show the "database result" in text please. I can think of a couple of ways to get that result, but, basically, we need to see your code in order to fix it. — Gert Arnold, Aug 31 '18 at 21:00

score 0 · Answer 1 · answered Aug 29 '18 at 13:46

I would be extra sure you are creating new objects for Version and isVersionOf in your WorkflowVersionLink object. If you are trying to make a copy of one, you may be referencing the same object by mistake.

modelBuilder.Entity<WorkflowVersionLink>()
.HasKey(t => t.WorkflowVersionLinkId );


modelBuilder.Entity<WorkflowVersionLink>()
  .HasOne(lk => lk.Version)
  .WithMany(wf => wf.VersionLinks)
  .HasForeignKey(lk => lk.VersionId);

modelBuilder.Entity<WorkflowVersionLink>()
.HasOne(lk => lk.IsVersionOf)
.HasForeignKey(lk => lk.IsVersionOfId)

You may still need to add constraints to keep your database clean

EFCore Many/One to Many relationship of the same entity

1 Answers1