" Hibernate.initialize() for each collection that will be needed in the web tier (this call must occur before the session is closed) or retrieves the collection eagerly using a query with a FETCH clause. "

-> the mapping file indicates lazy=true for the collection
-> I retreive a collection using the fetch and the collection is empty
(no associations in the database)
-> the parent object is sent along with this empty collection to another layer of the app
-> the other layer of the app attempts to use the empty collections to see if anything exists in it
-> a lazy intialization exception is thrown

is this the correct behaviour ? I thought if u used the fetch it would not try and lazy intialize the collection again . Is there any way around this . It works fine is there are assications in the database .

Thanks again

I don't believe you :)



Of course.

Show the stack trace.

I will have the stack trace first thing in the morning

this is the query
select user from User user left join fetch user.Group.roles where user.userId = :pk

the table structure is as follows


USER >- GROUP -< GROUPROLE >- ROLE

user can belong to one group a group can have many roles

Use

tried the many to many .. it still does not work

this is the error

net.sf.hibernate.LazyInitializationException: Failed to lazily initialize a collection - no session or session was closed
at net.sf.hibernate.collection.PersistentCollection.initialize(PersistentCollection.java:214)
at net.sf.hibernate.collection.PersistentCollection.read(PersistentCollection.java:71)
at net.sf.hibernate.collection.Set.size(Set.java:106)
at on.gov.ij.opp.scms.junit.testcases.UserManagerTest.testfindByPk(UserManagerTest.java:132)
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 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:392)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:276)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:167)



I was also always under the impression that

"HQL always ignores the mapping document outer join fetch setting"


I don't even see the SQL for the roles executing with the query I posted .. just one select for the user and once select for the group


Thanks again

Are you trying to acceed the lazy loaded collection AFTER the hibernate session is closed?

// Find user (Session is opend and closed in findby pk ... using fetch in query)
User user = userManager.findByPk(pk);

// Should have intialized group object
user.getAssignedGroup();

// Should have intialized roles ... throws lazy exeception
user.getAssignedGroup().getRoles()

But as Gavin has posted , if u use a fetch it should not try a lazy intialize the the collection again .. meaning the user.getAssignedGroup().getRoles()
should not throw a lazy exception even if the collection is null .. meaning there are no associations in the database ?

It works ! , I put the out-join inside the set as opposed to the many to many

<set name="roles" table="tblgrouprole" lazy="true" outer-join="true" >
<key column="groupid" />
<many-to-many class="Role"column="roleid" />
</set>

Thanks for all you fast replies , could somebody still explain this line

[/quote]HQL always ignores the mapping document outer join fetch setting , if you have mapped some association to be fetched by outer join (eg by setting outer-join="true" on the association mapping) , any HQL query will ignore this preference[quote]

I didn't put the outer-join in query cause I thought it would be ignored , I probably missing something with this statement .

Thanks again

what I thought was working before is not .. sorry

here are my mapping files

<-------------- User Mapping ----------------------------->

<class name="User" optimistic-lock="version" table="tblUserDetail" >

<id name="userDetailId" column="userdetailid" type="int">
<generator class="sequence">
<param name="sequence">tbluserdetail_seq</param>
</generator>
</id>

<version column="version" name="version" />

<property name="name">
<column name="dn" sql-type="varchar2(1000)" />
</property>

<property name="isActive">
<column name="isActive" sql-type="number(32)" />
</property>

<property name="groupID" >
<column name="groupid" sql-type="number(32)" />
</property>


<many-to-one name="assignedGroup" class="Group" column="groupid" insert="false" update="false" />

</class>

<-------------------------------- Group Mapping ----------------------------->


<class name="Group" optimistic-lock="version" table="tblgroup" >

<id name="groupID" column="groupid" type="int" unsaved-value="0" >
<generator class="sequence">
<param name="sequence">tblgroup_seq</param>
</generator>
</id>

<version column="version" name="version" />

<property name="name">
<column name="name" />
</property>

<property name="description">
<column name="description"/>
</property>

<property name="isActive">
<column name="isActive" />
</property>


<set name="roles" table="tblgrouprole" outer-join="true" lazy="true" >
<key column="groupid" />
<many-to-many outer-join="true" class="Role" column="roleid" />
</set>

</class>


<----------------------------- Role Mapping -------------------------------->

<hibernate-mapping auto-import="true">

<class name="Role" table="tblrole">

<id name="roleId" column="roleId" type="int">
<generator class="sequence">
<param name="sequence">tblrole_seq</param>
</generator>
</id>

<property name="roleName">
<column name="name" />
</property>

<property name="roleDesc">
<column name="description" />
</property>

<set name="groups" table="tblgrouprole" lazy="true">
<key column="roleid" />
<many-to-many class="Group" column="groupid" outer-join="true" />
</set>

</class>


The problem once again is as follows ... now that I have outer-join=true
(Both problems assume a user exists in the database with an assigned group .. but the group has no assigned roles)

-> dao get user object by calling the following query
" select user from User user where user.userDetailId = :pk "
-> another tier attempts to access the roles .. user.getAssignedGroup.getRoles()
-> Since I did not use the fetch in query I would have thought for sure I would get a lazy exception .. but I don't .. it returns 0 as the size of the collection cause no associations exist in the database

Second senario

-> dao get user object by calling the following query
" select user from User user left join fetch user.assignedGroup.roles where user.userDetailId = :pk"
-> another tier attempts to access the roles .. user.getAssignedGroup.getRoles()
-> Since I used the fetch in query lazy intialization is by-passed and no exception is thrown .. perfect .. what I expected (still no associations exist in the database)

if I take out the outer join in the set

then

-> dao get user object by calling the following query
" select user from User user where user.userDetailId = :pk "
-> another tier attempts to access the roles .. user.getAssignedGroup.getRoles()
-> Since I did not use the fetch it does THROW lazy exception .. what I thought


-> dao get user object by calling the following query
" select user from User user left join fetch user.assignedGroup.roles where user.userDetailId = :pk"
-> another tier attempts to access the roles .. user.getAssignedGroup.getRoles()
-> Since I did use the fetch I thought that it would not throw lazy exception but it does .





<class name="Group" optimistic-lock="version" table="tblgroup" >

<id name="groupID" column="groupid" type="int" unsaved-value="0" >
<generator class="sequence">
<param name="sequence">tblgroup_seq</param>
</generator>
</id>

<version column="version" name="version" />

<property name="name">
<column name="name" />
</property>

<property name="description">
<column name="description"/>
</property>

<property name="isActive">
<column name="isActive" />
</property>


<set name="roles" table="tblgrouprole" lazy="true" >
<key column="groupid" />
<many-to-many outer-join="true" class="Role" column="roleid" />
</set>

</class>