How to map recursive relation on self in Entity Framework code-first approach

Question

All I want to create is basic recursive category. Category is root if RootCategory_Id is set to null and it belongs to some other category if it is set to some

Answer 1

is lazy loading on or off?,

You may need to include the child relationship in the query like so

_db.Categories.Include("ChildCategories").FirstOrDefault(x => x.ID == 4)