Hi,
This is a newbie question, any help would be appreciated. I've read over the quickstart guide, FAQ, chapter 2 of the book, etc, and I must be missing something simple because I just can't get this association to work. The complete details are below: basically the classes and Hibernate access to them is working fine individually, but when I try to associate one to the other it a fails.
I have two database tables, Car and Trim, like so:
CREATE TABLE `cars` (
`id` int(10) unsigned NOT NULL auto_increment,
`make_id` int(10) unsigned NOT NULL default '0',
`model_id` int(10) unsigned NOT NULL default '0',
`year` int(10) unsigned NOT NULL default '0' COMMENT 'e.g. 1996'
)
CREATE TABLE `trims` (
`id` int(10) unsigned NOT NULL auto_increment,
`car_id` int(10) unsigned NOT NULL default '0',
`name` text NOT NULL,
`description` text NOT NULL COMMENT,
PRIMARY KEY (`id`),
KEY `FK_trims_1` (`car_id`),
CONSTRAINT `FK_trims_1` FOREIGN KEY (`car_id`) REFERENCES `cars` (`id`)
)
I have simple Java POJO classes for these, com.mycompany.Car and com.mycompany.Trim, following the JavaBean conventions as shown in the Hibernate reference documentation. I have Managers and unit tests for these classes that all work fine. The complete mapping files are below.
I'd like a unidirectional association from Car to Trims, i.e. one car has many trims. If I understand the Hibernate terminology correctly, Car is the parent, Trim is a child. This is a Set association, as there is some number of trims and the order does not matter.
So I added the following methods to thr Car class:
private Set trims = new HashSet();
public Set getTrims() { return trims; }
public void setTrims(Set trims) { this.trims = trims; }
*** This is where I need help: ***
What do I add to the Car.hbm.xml mapping files to make this work? I tried this and got the error shown below:
<set name="trims" inverse="true">
<key column="car_id"/>
<one-to-many class="com.mycompany.Trim"/>
</set>
Hibernate version: 3.1.2
Mapping documents:
<?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="com.mycompany.Car" table="CARS">
<id name="id" column="ID">
<generator class="native" />
</id>
<property name="makeId" column="MAKE_ID" />
<property name="modelId" column="MODEL_ID" />
<property name="year" />
</class>
</hibernate-mapping>
<?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="com.mycompany.Trim" table="TRIMS">
<id name="id" column="ID">
<generator class="native" />
</id>
<property name="carId" column="CAR_ID" />
<property name="name" />
<property name="description" />
</class>
</hibernate-mapping>
Full stack trace of any exception that occurs:
Mar 14, 2006 1:39:01 PM org.hibernate.LazyInitializationException <init>
SEVERE: failed to lazily initialize a collection of role: com.nimalex.domain.Car
.trims, no session or session was closed
org.hibernate.LazyInitializationException: failed to lazily initialize a collect
ion of role: com.nimalex.domain.Car.trims, no session or session was closed
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitia
lizationException(AbstractPersistentCollection.java:358)
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitia
lizationExceptionIfNotConnected(AbstractPersistentCollection.java:350)
at org.hibernate.collection.AbstractPersistentCollection.initialize(Abst
ractPersistentCollection.java:343)
at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPe
rsistentCollection.java:86)
at org.hibernate.collection.PersistentSet.toString(PersistentSet.java:25
3)
at java.lang.String.valueOf(String.java:2577)
at java.lang.StringBuilder.append(StringBuilder.java:116)
at com.nimalex.domain.Car.toString(Car.java:147)
at java.lang.String.valueOf(String.java:2577)
at java.lang.StringBuilder.append(StringBuilder.java:116)
at com.nimalex.domain.CarManagerTest.testGet(CarManagerTest.java:115)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at junit.framework.TestCase.runTest(TestCase.java:154)
at junit.framework.TestCase.runBare(TestCase.java:127)
at junit.framework.TestResult$1.protect(TestResult.java:106)
at junit.framework.TestResult.runProtected(TestResult.java:124)
at junit.framework.TestResult.run(TestResult.java:109)
at junit.framework.TestCase.run(TestCase.java:118)
at junit.framework.TestSuite.runTest(TestSuite.java:208)
at junit.framework.TestSuite.run(TestSuite.java:203)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.maven.surefire.battery.JUnitBattery.executeJUnit(JUnitBatt
ery.java:242)
at org.apache.maven.surefire.battery.JUnitBattery.execute(JUnitBattery.j
ava:216)
at org.apache.maven.surefire.Surefire.executeBattery(Surefire.java:215)
at org.apache.maven.surefire.Surefire.run(Surefire.java:163)
at org.apache.maven.surefire.Surefire.run(Surefire.java:87)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.maven.surefire.SurefireBooter.runTestsInProcess(SurefireBo
oter.java:285)
at org.apache.maven.surefire.SurefireBooter.run(SurefireBooter.java:201)
at org.apache.maven.test.SurefirePlugin.execute(SurefirePlugin.java:366)
at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPlugi
nManager.java:415)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(Defa
ultLifecycleExecutor.java:531)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLi
fecycle(DefaultLifecycleExecutor.java:472)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(Defau
ltLifecycleExecutor.java:451)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHan
dleFailures(DefaultLifecycleExecutor.java:303)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegmen
ts(DefaultLifecycleExecutor.java:270)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLi
fecycleExecutor.java:139)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:322)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:115)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:249)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Mar 14, 2006 1:39:01 PM com.nimalex.domain.CarManagerTest testGet
SEVERE: Failed test
org.hibernate.LazyInitializationException: failed to lazily initialize a collect
ion of role: com.nimalex.domain.Car.trims, no session or session was closed
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitia
lizationException(AbstractPersistentCollection.java:358)
at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitia
lizationExceptionIfNotConnected(AbstractPersistentCollection.java:350)
at org.hibernate.collection.AbstractPersistentCollection.initialize(Abst
ractPersistentCollection.java:343)
at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPe
rsistentCollection.java:86)
at org.hibernate.collection.PersistentSet.toString(PersistentSet.java:25
3)
at java.lang.String.valueOf(String.java:2577)
at java.lang.StringBuilder.append(StringBuilder.java:116)
at com.nimalex.domain.Car.toString(Car.java:147)
at java.lang.String.valueOf(String.java:2577)
at java.lang.StringBuilder.append(StringBuilder.java:116)
at com.nimalex.domain.CarManagerTest.testGet(CarManagerTest.java:115)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at junit.framework.TestCase.runTest(TestCase.java:154)
at junit.framework.TestCase.runBare(TestCase.java:127)
at junit.framework.TestResult$1.protect(TestResult.java:106)
at junit.framework.TestResult.runProtected(TestResult.java:124)
at junit.framework.TestResult.run(TestResult.java:109)
at junit.framework.TestCase.run(TestCase.java:118)
at junit.framework.TestSuite.runTest(TestSuite.java:208)
at junit.framework.TestSuite.run(TestSuite.java:203)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.maven.surefire.battery.JUnitBattery.executeJUnit(JUnitBatt
ery.java:242)
at org.apache.maven.surefire.battery.JUnitBattery.execute(JUnitBattery.j
ava:216)
at org.apache.maven.surefire.Surefire.executeBattery(Surefire.java:215)
at org.apache.maven.surefire.Surefire.run(Surefire.java:163)
at org.apache.maven.surefire.Surefire.run(Surefire.java:87)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.maven.surefire.SurefireBooter.runTestsInProcess(SurefireBo
oter.java:285)
at org.apache.maven.surefire.SurefireBooter.run(SurefireBooter.java:201)
at org.apache.maven.test.SurefirePlugin.execute(SurefirePlugin.java:366)
at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPlugi
nManager.java:415)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(Defa
ultLifecycleExecutor.java:531)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLi
fecycle(DefaultLifecycleExecutor.java:472)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(Defau
ltLifecycleExecutor.java:451)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHan
dleFailures(DefaultLifecycleExecutor.java:303)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegmen
ts(DefaultLifecycleExecutor.java:270)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLi
fecycleExecutor.java:139)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:322)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:115)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:249)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Name and version of the database you are using:
MySQL 5.0.18-nt
The generated SQL (show_sql=true):
Hibernate: select car0_.ID as ID0_, car0_.MAKE_ID as MAKE2_0_, car0_.MODEL_ID as
MODEL3_0_, car0_.year as year0_ from CARS car0_ where car0_.MAKE_ID=2 and car0_
.MODEL_ID=2 and car0_.year=1964
Again, any help would be appreciated. Thank you in advance,
Yoav Shapira
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