Map marked as lazy="false" is lazy instanciated

tnine · **Joined:** Fri Feb 13, 2004 10:02 pm **Posts:** 90

Read the rules before posting!
http://www.hibernate.org/ForumMailingli ... AskForHelp

Hibernate version:
3.01
Mapping documents:

Code:

<hibernate-mapping package="com.llic.calc.label">
  <class name="Label" table="Label">
  
    <id name="id" column="labelid" type="java.lang.Long">
      <generator class="native" />
    </id>
        
    <property name="name" column="name" type="string" unique="true"/>
    
   <many-to-one name="equation" class="com.llic.calc.variable.EquationVariable" lazy="false"/>
   
   <!-- map of database labels -->
   <map name="dbVar" lazy="false">
      <key column="labelid"/>
      <map-key type="java.lang.Long" column="dbvarid"/>
      <element type="java.lang.Long" column="rowId"/>
   </map>
    
  </class>
</hibernate-mapping>

Code between sessionFactory.openSession() and session.close():
String hql = "from " + getBusinessClass() + " as label where label.name = :name";

List results = getHibernateTemplate().findByNamedParam(hql, "name", name);

return (Label) getFirstResult(results);

Full stack trace of any exception that occurs:

Code:

org.hibernate.LazyInitializationException: could not initialize proxy - the owning Session was closed
   at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:53)
   at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:80)
   at org.hibernate.proxy.CGLIBLazyInitializer.intercept(CGLIBLazyInitializer.java:134)
   at com.llic.calc.variable.EquationVariable$$EnhancerByCGLIB$$95da3f81.getVariables(<generated>)
   at com.llic.calc.LabelPreparer.prepareEquation(LabelPreparer.java:48)
   at com.llic.calc.LabelPreparer.applyLabel(LabelPreparer.java:38)
   at com.llic.calc.EquationFactory.getLabeledEquation(EquationFactory.java:224)
   at com.llic.calc.LabelingTest.testLabelAdd(LabelingTest.java:81)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
   at java.lang.reflect.Method.invoke(Method.java:324)
   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 org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:474)
   at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:342)
   at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:194)

Name and version of the database you are using:
MySQL 4.0
The generated SQL (show_sql=true):

Code:

select dbvar0_.labelid as labelid__, dbvar0_.rowId as rowId__, dbvar0_.dbvarid as dbvarid__ from ides_dbVar dbvar0_ where dbvar0_.labelid=?

Hibernate is lazy loading the map. I explicity set lazy="false" in the mapping, since I do not want to lazy load the map. The session is closed when the map is utilized in our logic, and we will always use all of the entries. Should I report this as a bug in Jira, or did I simply overlook something obvious?
[/code]

Gottin · **Joined:** Wed Mar 02, 2005 6:28 pm **Posts:** 13

well, I think you don't understent clearly what "lazy" means.

lazy="true"
-> you load the data only if you need it.
-> you can access the data only while in persistent mode (after new Transaction and before Transaction.commit() )

lazy="false"
-> you are loading the whole state of the object when you load it , including all elements/values of the map.

I hope it was a help for you

anthony · **Posted:** Mon Apr 18, 2005 11:34 am

forget about lazy and focus on fetch attribute:
fetch="select" means lazy behaviour
fetch="join" means eager loading behaviour

change

Code:

   <map name="dbVar" lazy="false"> 
      <key column="labelid"/> 
      <map-key type="java.lang.Long" column="dbvarid"/> 
      <element type="java.lang.Long" column="rowId"/> 
   </map> 

to

Code:

   <map name="dbVar" fetch="join"> 
      <key column="labelid"/> 
      <map-key type="java.lang.Long" column="dbvarid"/> 
      <element type="java.lang.Long" column="rowId"/> 
   </map> 

tnine · **Joined:** Fri Feb 13, 2004 10:02 pm **Posts:** 90

Anthony,
Thanks for the help, I've been using hibernate since version 2.x, where the lazy attribute was capable of specifying this behavior. Will the documentation to collections be updated for Hibernate 3 to relfect this change in mapping?

Todd

tnine · **Joined:** Fri Feb 13, 2004 10:02 pm **Posts:** 90

No dice. I'm still getting the same error. As I said before, the map needs to be loaded completely for access outside of the session scope. I need to have the non-lazy load behavior, and it seems that all attributes are not working correctly

gavin · **Posted:** Mon Apr 18, 2005 12:12 pm

Don't believe you. I got unit tests that show this stuff is all working.

tnine · **Joined:** Fri Feb 13, 2004 10:02 pm **Posts:** 90

Ok, Gavin was correct, the problem does lie somehere else. If you look at the original stacktrace

Code:

at com.llic.calc.variable.EquationVariable$$EnhancerByCGLIB$$95da3f81.getVariables(<generated>)
   at com.llic.calc.LabelPreparer.prepareEquation(LabelPreparer.java:48) 

You can see that the problem comes when label.getEquation().getVariables is called. It is nothing wrong with the map, however, the many-to-one relation is being lazy loaded when I have specified lazy="false". I have also tried replacing lazy="false" with fetch="join". It appears that I am getting a cglib proxy for my EquationVariable instance, shouldn't lazy="false" just get me the loaded POJO? I have attached my EquationVariable mapping.

Code:

<hibernate-mapping package="com.llic.calc.variable">
  <joined-subclass name="EquationVariable" table="EquationVariable" extends="Variable">
     
      <key column="variableId"/>
    
         
      <property name="expressionString" column="expressionString" type="string" length="500"/>
   
      <map name="expressionVariables" cascade="all" lazy="false">
         <key column="equationVariableId"/>
         <map-key  type="string" column="variableName"/>
         <one-to-many class="Variable"/>      
      </map>
   
      <!-- custom persister -->
    <property name="returnType" column="returnType" type="com.llic.calc.dao.hibernate.type.InterfacePersister"/>
   
    
  </joined-subclass> 
</hibernate-mapping>

gavin · **Posted:** Mon Apr 18, 2005 1:04 pm

Read the documentation and understand the difference between

<many-to-one lazy="false"/>

and

<class lazy="false">

tnine · **Joined:** Fri Feb 13, 2004 10:02 pm **Posts:** 90

OK, from my understanding of reading the documentation here is what I am trying to do.

All properties of class Label need to be eagerly loaded. I can either set lazy="false" at the class level of class com.llic.calc.label.Label, or set lazy="false" on each property. I have tried to set lazy="false" globally, and I am still receiving the cglib proxy exception when I call label.getEquation(). What the heck am I doing wrong? I've never had this much trouble getting mappings correct, and this is driving me nuts! I thought that by setting lazy="false" at the class level for com.llic.calc.label.Label, that all properties would be intanciated when the Label class is instanciated. Obviously I'm making a mistake, do you see anything obvious?

gavin · **Posted:** Mon Apr 18, 2005 1:50 pm

Listen, you need to go and buy yourself a copy of Hibernate in Action and read it, then check out the diffs between HB2 and HB3 and then try to understand before posting frustrated semi-understood problem descriptions here.

P.S. You can solve your problem trivially just by mapping

<class name="EquationVariable" lazy="false">

tnine · **Joined:** Fri Feb 13, 2004 10:02 pm **Posts:** 90

Gavin,
I do have hibernate in action, its a good book ;-). I tried setting the EquationVariable to lazy, but I received errors about proxy instanciation due to it being a joined subclass. I will review the book on joined-sublcass objects as well as lazy instanciation and try to get a grasp on this.

Todd