Hallo,
ich habe eine Frage zum lazy fetching.
Ich habe eine Containerklasse, die quasi die Objecte der Datenbank zwischenspcihert, damit nicht immer eine DB gamacht werden muss.
Die Person oder eine Subclass davon hat auch one-to-many oder many-to-many assoziationen.
Mit der Doku bin ich schonmal soweit gekommen, dass Hibernate mittels lazy associations arbeitet.
Also wenn ich Alle Personen lese werden nicht alle assoziatinsobjekte gelesen.
Wenn ich aber nun die Objeke in einem JTree darstellen will, dann werden die anderen Assoziationen z. T. ja erst gelesen, wenn die session schon geschlossen ist. (Deswegen ja auch die Exception)
Gibt es denn noch andere Möglichkeiten, ausser die Fetch-Strategie umzustellen, dass man alle Objekte zusammen ausliest.
Weil wenn ich die fetch strategie umstelle, dann habe ich ja IMME alle Objekte im Speicher und nicht nur dann, wenn ich sie brauche.
Ich hoffe man kann mein problem verstehen.
Und ich hoffe noch mehr, dass man mir helfen kann :-)
Nun noch ein paar Files, die zu dem problem führen.
Hibernate version: 3
Mapping documents:
Code:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="name.pawlitzki.kita.objects.person.Person" table="PERSONS">
<id name="id" column="person_id" type="long">
<generator class="identity"/>
</id>
<property name="birthday" type="date"/>
<property name="gender"/>
<one-to-one
name="name"
class="name.pawlitzki.kita.objects.person.Name"
constrained="true"
cascade="all" />
<many-to-one
name="religion"
column="religion_id"
class="name.pawlitzki.kita.objects.person.Religion"
update="true"
insert="true"
cascade="all"/>
<many-to-one
name="address"
column="address_id"
class="name.pawlitzki.kita.objects.person.Address"
update="true"
insert="true"
cascade="all"/>
<!-- BEGIN Parent -->
<joined-subclass name="name.pawlitzki.kita.objects.person.Parent" table="PARENTS">
<key column="person_id"/>
<property name="occupation"/>
<set name="contacts" table="PARENTS_CONTACTS" cascade="all">
<key column="person_id"/>
<many-to-many
column="contact_id"
class="name.pawlitzki.kita.objects.person.Contact"/>
</set>
<set name="relations" cascade="all">
<key column="person_id"/>
<one-to-many class="name.pawlitzki.kita.objects.person.Relation"/>
</set>
</joined-subclass>
<!-- END Parent -->
<!-- BEGIN NurseryPerson -->
<joined-subclass name="name.pawlitzki.kita.objects.person.NurseryPerson" table="NURSERY_PERSONS">
<key column="person_id"/>
<property name="fromDate" type="date"/>
<property name="untilDate" type="date"/>
<set name="absencePeriods">
<key column="person_id"/>
<one-to-many class="name.pawlitzki.kita.objects.person.AbsencePeriod"/>
</set>
<!-- BEGIN Child -->
<joined-subclass name="name.pawlitzki.kita.objects.person.Child" table="CHILDS">
<key column="person_id"/>
<many-to-one
name="group"
column="group_id"
class="name.pawlitzki.kita.objects.person.Group"/>
<set name="relations">
<key column="person_id"/>
<one-to-many class="name.pawlitzki.kita.objects.person.Relation"/>
</set>
</joined-subclass>
<!-- END Child -->
<!-- BEGIN Employee -->
<joined-subclass name="name.pawlitzki.kita.objects.person.Employee" table="EMPLOYEES">
<key column="person_id"/>
<property name="leaveDays"/>
<property name="role"/>
<set name="groupFunctions">
<key column="person_id"/>
<one-to-many class="name.pawlitzki.kita.objects.person.GroupFunction"/>
</set>
</joined-subclass>
<!-- END Employee -->
</joined-subclass>
<!-- BEGIN NurseryPerson -->
</class>
</hibernate-mapping>
Code:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="name.pawlitzki.kita.objects.person.AbsencePeriod" table="ABSENCE_PERIODS">
<id name="id" column="id" type="long">
<generator class="identity"/>
</id>
<property name="fromDate" type="date"/>
<property name="untilDate" type="date"/>
<property name="reason"/>
<many-to-one
name="nurseryPerson"
column="nursery_person_id"
class="name.pawlitzki.kita.objects.person.NurseryPerson"/>
</class>
</hibernate-mapping>
Code:
private void refresh() {
Session session = HibernateUtil.currentSession();
Transaction tx = session.beginTransaction();
List persons = session.createQuery("from Person").list();
tx.commit();
HibernateUtil.closeSession();
boolean added = this.persons.addAll(persons);
if (added) {
setChanged();
notifyObservers();
}
}
Full stack trace of any exception that occurs:
Quote:
Hibernate: select person0_.person_id as person1_0_, person0_.birthday as birthday0_, person0_.gender as gender0_, person0_.religion_id as religion4_0_, person0_.address_id as address5_0_, person0_1_.occupation as occupation1_, person0_2_.fromDate as fromDate3_, person0_2_.untilDate as untilDate3_, person0_3_.group_id as group2_4_, person0_4_.leaveDays as leaveDays5_, person0_4_.role as role5_, case when person0_3_.person_id is not null then 3 when person0_4_.person_id is not null then 4 when person0_1_.person_id is not null then 1 when person0_2_.person_id is not null then 2 when person0_.person_id is not null then 0 end as clazz_ from PERSONS person0_ left outer join PARENTS person0_1_ on person0_.person_id=person0_1_.person_id left outer join NURSERY_PERSONS person0_2_ on person0_.person_id=person0_2_.person_id left outer join CHILDS person0_3_ on person0_.person_id=person0_3_.person_id left outer join EMPLOYEES person0_4_ on person0_.person_id=person0_4_.person_id
2005-10-28 13:29:41,888 [AWT-EventQueue-0] ERROR (LazyInitializationException.java:19) - failed to lazily initialize a collection of role: name.pawlitzki.kita.objects.person.NurseryPerson.absencePeriods, no session or session was closed
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: name.pawlitzki.kita.objects.person.NurseryPerson.absencePeriods, no session or session was closed
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:358)
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:350)
at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:343)
at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:86)
at org.hibernate.collection.PersistentSet.iterator(PersistentSet.java:138)
at name.pawlitzki.kita.gui.tree.NurseryPersonTreeNode.<init>(NurseryPersonTreeNode.java:20)
at name.pawlitzki.kita.gui.tree.ChildTreeNode.<init>(ChildTreeNode.java:22)
at name.pawlitzki.kita.gui.ChildrenTreeInternalFrame.addChild(ChildrenTreeInternalFrame.java:120)
at name.pawlitzki.kita.gui.ChildrenTreeInternalFrame.readChildren(ChildrenTreeInternalFrame.java:104)
at name.pawlitzki.kita.gui.ChildrenTreeInternalFrame.<init>(ChildrenTreeInternalFrame.java:81)
at name.pawlitzki.kita.gui.KITAMainFrame$MenuBarActionListener.actionPerformed(KITAMainFrame.java:148)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1849)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2169)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
at javax.swing.AbstractButton.doClick(AbstractButton.java:302)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:1000)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:1041)
at java.awt.Component.processMouseEvent(Component.java:5488)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3126)
at java.awt.Component.processEvent(Component.java:5253)
at java.awt.Container.processEvent(Container.java:1966)
at java.awt.Component.dispatchEventImpl(Component.java:3955)
at java.awt.Container.dispatchEventImpl(Container.java:2024)
at java.awt.Component.dispatchEvent(Component.java:3803)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4212)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3892)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3822)
at java.awt.Container.dispatchEventImpl(Container.java:2010)
at java.awt.Window.dispatchEventImpl(Window.java:1774)
at java.awt.Component.dispatchEvent(Component.java:3803)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)
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