Updating in hibernate
The first step in transforming our unidirectional relationship into a bidirectional relationship is to add the missing reference from the .
You can't just set a few of them and assume that Hibernate will figure out which ones to update and which ones to not update. Instead of:and nothing more is needed (assuming that your transaction is committed somewhere).When we have a bidirectional relationship between objects, it means that we are able to access Object A from Object B, and Object B from Object A. This means that we need to populate both the Note: To observe best coding practices, the code I’ve put into this Controller class is usually best placed in a Service class, but to keep things as simple as possible for this tutorial I’ve just placed all the code directly into the Controller. When you do you’ll instantly receive one free gift from me (and plenty more in the future). We can apply this logic to our real world coding example that we saw in the last post. Many To One; @Entity public class Employee objects into the database in a unidirectional manner… now that we’ve changed our code around to use a bidirectional relationship, we need to change the way we persist our data. Repository; import org.springframework.transaction.annotation. Transactional; import com.howtoprogramwithjava.example.persistence. Employer; @Transactional @Repository public class Employer Dao Now the only missing piece is to show you how to actually persist data using this new bidirectional One-to-Many mapping. For example, I don't know what will happen with cascades to associations or collections.The key to this is that the call to session.lock() associates the entity with the session and also sets the initial state.