Question

On the database, I have these two tables:

- Destination:
 - idDestination
 - name

- Airport:
 - idAirport
 - idDestination // FK into Destination city
 - name

where:

• 1 Destination(read: city) has many Airports
• 1 Airport belongs to 1 City
• Hence: 1-Many relation between Destination-Airports

---

My Java classes look like this:

class Destination{
 private Integer idDestination;
 private String name;

 // getter and setters
}

class Airport{
 private Integer idAirport;
 private Destination city;
 private String name;
}

// Separate class for airports in city, since city is being used in a lot of other places
// and I'd like to keep Destination class clean
class CityAirports{
 private Destination City;
 private Set<Airport> airports;
}

---

Hibernate Mappings: Airport.hbm.xml

<hibernate-mapping>
    <class name="org.wah.dao.Airport" table="AIRPORT">
        <id name="idAirport" type="java.lang.Integer">
            <column name="IDAIRPORT" />
            <generator class="identity" />
        </id>
        <property name="name" type="java.lang.String">
            <column name="NAME" />
        </property>
        <many-to-one name="city" class="org.wah.dao.Destination">
            <column name="IDCITY" />
        </many-to-one>
    </class>
</hibernate-mapping>

---

I need to define another mapping for CityAirports to
– retrieve all the airports within the city.
– add a new airport to the city.

I am not sure what the hibernate mapping would look like ? Can someone please guide me on how to do it?

Answer 1

for destination mapping,

<hibernate-mapping>
 <class name="org.wah.dao.Destination" table="DESTINATION">
 <id name="idDestination" type="int" column="DESTINATION_ID">
     <generator class="native" />
 </id>
 <property name="name" type="string" not-null="true" length="100" 
    column=DESTINATION_NAME" />
 <set name="destinationAirPorts" table="DESTINATION_AIRPORT" cascade="all">
  <key column="DESTINATION_ID" />
  <many-to-many column="IDAIRPORT" unique="true" class="org.wah.dao.Airport" />
 </set>
</class>

for airport mapping,

<hibernate-mapping>
 <class name="org.wah.dao.Airport" table="AIRPORT">
 <id name="idAirport" type="int" column="IDAIRPORT">
     <generator class="native" />
 </id>
 <property name="name" type="string" not-null="true" length="100" 
    column=NAME" />

</class>
</hibernate-mapping>