Hibernate, insert or update without select

Question

I have a products objects which belongs to certain categories i.e. classical many to one relationship.

@Entity
public class Product{

    @Id
    @GeneratedValue         


        

Answer 1

session.load() exists specifically for cases like this. The following:

Category category = session.load(categoryId);
product.setCategory(category);

will not hit the database. It will, however, throw an exception at a later stage (during flush, more or less) if there is no category available with given id.

Using load() is faster than merge() and has no side-effects (cascading, etc...)