inserting values into multiple tables using hibernate

Question

hello everyone,

i have existing tables hotel and hotel_services.

hotel table contains:
hotel_id
hotel_name

hotel_services contains:
hotel_id
hotel_service_name

each hotel can offer several services, so in my form user could enter as many services as he wants at a time.
so for instance,
hotel name: HOTEL1
hotel_services:
1. hotel_service1
2. hotel_service2
3. hotel_service3

my question is how should i do it in hibernate in such a way that i'll be able to insert all the data into their respective tables(which are hotels and hotel_services tables).

thanks for the help.. 

Answer 1

What you're describing is a basic OneToMany relation between an Hotel and Services and the mapping would look like this (I'll map it as a bidirectional association, using annotations):

@Entity
public class Hotel {
    @Id @GeneratedValue
    private Long id;

    @OneToMany(cascade=ALL, mappedBy="hotel")
    Set<Service> services = new HashSet<Service>();

    // other attributes, getters, setters

    // method to manage the bidirectional association
    public void addToServices(Service service) {
        this.services.add(service);
        service.setHotel(this);
}

@Entity
public class Service {
    @Id @GeneratedValue
    private Long id;

    @ManyToOne
    private Hotel hotel;

    // getters, setters, equals, hashCode
}

And here is a snippet demonstrating how to use this:

SessionFactory sf = HibernateUtil.getSessionFactory(); // this is a custom utility class
Session session = sf.openSession(); 
session.beginTransaction();

Hotel hotel = new Hotel();
Service s1 = new Service();
Service s2 = new Service();
hotel.addToServices(s1);
hotel.addToServices(s2);
session.persist(hotel);

session.getTransaction().commit();
session.close();

To go further (because I won't explain everything in this answer), have a look at:

• Hibernate Getting Started Guide (covers the Native API with XML mappings, the Native API with annotations, the JPA API)
• Hibernate Core Reference Guide
  • Chapter 1. Tutorial