lazy loading not working in hibernate 3

[kishore mang]

Hi all,

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping 
PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" 
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="Event" table="events">
		<id name="id" column="uid" type="long" unsaved-value="null">
			<generator class="increment" />
		</id>
		<property name="name" type="string" length="100" />
		<property name="startDate" column="start_date" type="date" />
		<property name="duration" type="integer" />
		<many-to-one name="location" column="location_id" class="Location"/>
		<set name="speakers" cascade="all">
			<key column="event_id" />
			<one-to-many class="Speaker" />
		</set>
		<set name="attendees" cascade="all">
			<key column="event_id" />
			<one-to-many class="Attendee" />
		</set>
	</class>
</hibernate-mapping>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping 
PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" 
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="Attendee" table="attendees">
        <id name="id" column="uid" type="long">
            <generator class="increment"/>
        </id>
        <property name="firstName" type="string" length="20"/>
        <property name="lastName" type="string" length="20"/>
    </class>
</hibernate-mapping>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping 
PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" 
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="Location" table="locations">
        <id name="id" column="uid" type="long">
            <generator class="increment"/>
        </id>
        <property name="name" type="string"/>
        <property name="address" type="string"/>
    </class>
</hibernate-mapping>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping 
PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" 
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="Speaker" table="speakers">
        <id name="id" column="uid" type="long">
            <generator class="increment"/>
        </id>
        <property name="firstName" type="string" length="20"/>
        <property name="lastName" type="string" length="20"/>
    </class>
</hibernate-mapping>

and my entity objects:

public class Event {

	private Long id;
	private String name;
	private Date startDate;
	private int duration;
	private Set speakers;
    private Set attendees;
    private Location location;

    public Event(){}
}

public class Speaker {

    private Long id;
    private String firstName;
    private String lastName;

    public Speaker() {
    }
}

public class Attendee {

    private Long id;
    private String firstName;
    private String lastName;

    public Attendee() {
    }
}

public class Location {
    private Long id;
    private String name;
    private String address;
}

when i run following statement it fetching child/referenced objects too which i dont want

Event event = (Event) session.get(Event.class, 1L);
		System.out.println("##event=" + event);

##event=Event [id=1, name=Thanks giving day, startDate=null, duration=0, 
speakers=[Speaker [id=1, firstName=second, lastName=sec], 
Speaker [id=2, firstName=kk, lastName=mm]], 
attendees=[Attendee [id=2, firstName=james, lastName=mike], 
Attendee [id=1, firstName=victor, lastName=wine]], 
location=Location [id=1, name=London, address=lon]]

any suggestions where things going wrong? please suggest.

Regards
Kishore

[Kathleen Angeles]

Where did you get the data you used to print below?

##event=Event [id=1, name=Thanks giving day, startDate=null, duration=0, 
speakers=[Speaker [id=1, firstName=second, lastName=sec], 
Speaker [id=2, firstName=kk, lastName=mm]], 
attendees=[Attendee [id=2, firstName=james, lastName=mike], 
Attendee [id=1, firstName=victor, lastName=wine]], 
location=Location [id=1, name=London, address=lon]]

If it is from the same 'event' object instance returned by hibernate, and if at that moment that object is still managed by hibernate, you will inadvertently load the data.

[kishore mang]

Hi Kathleen,

appreciate for your quick response, even i removed toString() in all classes still able to see
in debug view the event object and its all child objects loaded with all values set.

So i am sure that returned session.get() which is event is loaded all its child objects.
This means eclipse debug view loading all referenced child objects?

Regards
Kishore

[Kathleen Angeles]

Yes, it is possible that is the eclipse debug mode that loads it.

Quite dirty, but just to see that those data are really lazily-loaded: disable the debug mode of eclipse, after getting the 'event' object from hibernate, terminate or close the hibernate session, then try display the supposed-to-be lazily-loaded data. You should get an exception or null, showing that it was never loaded by hibernate.

[kishore mang]

you are right!!!
after session closed in eclipse debug mode i can see message about all referenced objects
as "com.sun.jdi.InvocationException occurred invoking method", means referenced data not loaded.

i never expected that eclipse debug mode causing referenced data get loaded by parent.