How to handle required vs optional relationships?

Short answer: In Fluent API: Required: .HasRequired(p => p.Blog) Optional: .HasOne(p => p.Blog) .WithMany() .IsRequired(false); EF infers: Reference type (e.g., Blog) → optional by default Non-nullable value type FK (e.g., int BlogId) → required Entity Framework Core – Lazy vs Eager vs Explicit Loading

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.