Why is Hibernate @OnetoMany relationship required?

Question

I have two entities Library and Books which are associated by Hibernate @OneToMany in a spring boot project. Fetching books in a particular library through the getter functions renders a LazyInitialisationException. The solution that I could find was making a query in the Books entity and fetching all the books corresponding to the library-id of the library. So, I was thinking why is oneToMany relationship required if we can just store a key corresponding to library in the Books table.

Answer 1

Simply storing a key doesn't provide any consistency assurances. Also, using defined OneToMany or ManyToOne you can also define the cascade types (you would only need to save the parent entity and then all the children would automatically be saved, in a single transaction). The quick way to fix your problem would be to use FetchType EAGER, but I would recommend fixing whatever you have misconfigured.