Multiple sql inserts in spring boot - spring-boot

Question

I have a code as following :
Offre o = offreRepository.save(offre);
for(OffreCompetence offreCompetence : offre.getOffreCompetences()) {
offreCompetence.setOffre(o);
offreCompetenceRepository.save(offreCompetence);
}
So as you can see I'm calling the offreRepository for the first time to insert an Offre into database, then I call offreCompetenceRepository multiple times to insert each OffreCompetencein the Offre to the database.
The problem here is that I'm making a connection to the database multiple times.
Isn't there any other method to do these inserts in once ?
Edit :
I tried to add this line :
#OneToMany(cascade = CascadeType.ALL, mappedBy="offre")
private Set<OffreCompetences> offreCompetences;
But the offreCompetences are not added to the database, when I checked the log file I noticed that Hibernate doesn't INSERT them but I can't find them in the database, I think the problem is when he try to add offreCompetences he doesn't know the id of the Offre for them :
Hibernate: insert into offre (date_expiration, date_publication, duree_mission, email_sended, etat, niveau_experience, nombre_postulant, nombre_vue, poste, profil_recherche, titre, code_type_contrat, code_ville) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
2016-07-28 16:08:13.237 DEBUG 10736 --- [nio-8080-exec-4] org.hibernate.SQL : insert into offre_competence (competence, niveau_requis, offre) values (?, ?, ?)
Hibernate: insert into offre_competence (competence, niveau_requis, offre) values (?, ?, ?)
2016-07-28 16:08:13.304 DEBUG 10736 --- [nio-8080-exec-4] org.hibernate.SQL : insert into offre_competence (competence, niveau_requis, offre) values (?, ?, ?)
Hibernate: insert into offre_competence (competence, niveau_requis, offre) values (?, ?, ?)
2016-07-28 16:08:13.339 DEBUG 10736 --- [nio-8080-exec-4] org.hibernate.SQL : insert into offre_competence (competence, niveau_requis, offre) values (?, ?, ?)
Hibernate: insert into offre_competence (competence, niveau_requis, offre) values (?, ?, ?)

Answer 1

You need to ensure that the parent object is set in every object in the list. The Cascade persist will ensure that the object and its children are saved and linked correctly. Unfortunately, if it is not explicitly set it will not create the relationship in the database.
for(OffreCompetence offreCompetence : offre.getOffreCompetences()) {
offreCompetence.setOffre(offre);
}
Offre o = offreRepository.save(offre);

Answer 2

Set the CascadeType on the offre.offreCompetences relationship.
#Entity
public class Offre {
#OneToMany(cascade = CascadeType.ALL, mappedBy="offre")
private Set<OffreCompetences> offreCompetences
...
}
#Entity
public class OffreCompetences {
#ManyToOne
#JoinColumn(name = "..." )
private Offre offre;
}
Once you do this, offreCompetences will be saved when you save offre.
Look at the JPA docs for CascadeType.