WithOptional with Entity Framework Core

Question

I'm trying to migrate my old app to the new EF Core but I cannot find some relationships like:

  HasRequired(o => o.Document).WithOptional(o => o.CancelNote);

Is there some extension methods? I cannot find on the docs.

The HasRequired I think that is possible to substitute with HasOne() method, but how about the WithOptional()?

Other thing, according to the docs the entity not uses the virtual keyword to create the navigation properties, how lazy load will work?

Can you please provide class declaration for Document and CancelNote — Karthic G, Feb 25 '21 at 10:13

ocuenca · Accepted Answer · 2016-07-21T20:44:45.013

33

You will not find an HasOptional equivalent method in EF7. By convention if your FK property is nullable, you navigation property will be treated as optional

 modelBuilder.Entity<Blog>()
                .HasOne(p => p.Document)
                .WithOne(i => i.CancelNote)
                .HasForeignKey<Document>(b => b.CancelNoteForeignKey);

About your second question,EF Core (EF7) doesn't support Lazy Loading. In this link you will find the options you have now to load related entities

edited Jul 21 '16 at 20:44

answered Jul 21 '16 at 20:38

ocuenca

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But my FK property is the Document entity: *public virtual Document Document {get;set;}* This property should be nullable? – gog Jul 21 '16 at 20:56
No, what you are pointing out is a navigation property, your FK property should be: `public int? CancelNoteForeignKey{get;set;}` – ocuenca Jul 21 '16 at 20:58
Does the HasOne() is replacement for HasOptional()? – Karthic G Jan 05 '21 at 16:52
How to specify HasForeignKey without knowing class models and Foreign property – Karthic G Mar 05 '21 at 10:34
Can you please provide the Class model for regarding this relationship, so easy to understand the concept – Karthic G Mar 05 '21 at 10:39

WithOptional with Entity Framework Core

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