loadByUniqueKey error and many-to-many w/join table.

merkkila · **Joined:** Fri Jul 15, 2005 10:02 am **Posts:** 12

using hibernate 3.2.1

I am mapping a many-to-many collection across a join table. Everything seems to load the proper data but I can not figure out why this error is getting generated. Any ideas would be greatly appreciated.

mappings

Code:

<class name="model.aws.AwsChannel" table="TBLCHANNEL">
        <id name="id" column="CHANNELID">
         <generator class="assigned" />
        </id>
        <property name="siteId" column="SITEID" />
        <property name="parentChannelId" column="PARENTCHANNELID" />
        <property name="legacyId" column="LEGACY_ID" />
        <property name="name" column="NAME" />
        <property name="description" column="DESCRIPTION" />
        <property name="active" column="ISACTIVE" />
        <property name="userCreated" column="USER_CREATED" />
        <property name="userModified" column="USER_MODIFIED" />
        <property name="dateCreated" column="DATE_CREATED" />
        <property name="dateModified" column="DATE_MODIFIED" />

        <set name="permissionSet" table="TBLCHANNELCONTENTMAPPING" where="guid in (select a.guid from bnp_permissions a)">
            <key column="CHANNELID" />
             <many-to-many column="GUID" property-ref="guid" not-found="ignore" class="model.security.Permission" />
        </set>

    </class>

<class name="model.security.Permission" table="BNP_PERMISSIONS">
        <id name="id" column="PERMISSION_ID">
         <generator class="assigned"/>
        </id>
        <property name="guid" column="GUID" unique="true" not-null="true" />
        <property name="title" column="TITLE" />
        <property name="plevel" column="PLEVEL" />
        
    </class>

log output

Code:

2007-01-05 12:58:35,277 DEBUG [org.hibernate.loader.Loader] loading collection: [model.aws.AwsChannel.permissionSet#23601]
2007-01-05 12:58:35,277 DEBUG [org.hibernate.jdbc.AbstractBatcher] about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
2007-01-05 12:58:35,277 DEBUG [org.hibernate.SQL] select permission0_.CHANNELID as CHANNELID1_, permission0_.GUID as GUID1_, permission1_.PERMISSION_ID as PERMISSION1_27_0_, permission1_.GUID as GUID27_0_, permission1_.TITLE as TITLE27_0_, permission1_.PLEVEL as PLEVEL27_0_ from TBLCHANNELCONTENTMAPPING permission0_ left outer join BNP_PERMISSIONS permission1_ on permission0_.GUID=permission1_.GUID where  ( permission0_.guid in (select a.guid from bnp_permissions a))  and permission0_.CHANNELID=?
2007-01-05 12:58:35,277 DEBUG [org.hibernate.jdbc.AbstractBatcher] preparing statement
2007-01-05 12:58:35,277 DEBUG [org.hibernate.type.LongType] binding '23601' to parameter: 1
2007-01-05 12:58:35,277 DEBUG [org.hibernate.jdbc.AbstractBatcher] about to open ResultSet (open ResultSets: 0, globally: 0)
2007-01-05 12:58:35,277 DEBUG [org.hibernate.loader.Loader] result set contains (possibly empty) collection: [model.aws.AwsChannel.permissionSet#23601]
2007-01-05 12:58:35,277 DEBUG [org.hibernate.engine.CollectionLoadContext] uninitialized collection: initializing
2007-01-05 12:58:35,277 DEBUG [org.hibernate.loader.Loader] processing result set
2007-01-05 12:58:35,277 DEBUG [org.hibernate.loader.Loader] result set row: 0
2007-01-05 12:58:35,277 DEBUG [org.hibernate.type.LongType] returning '2' as column: PERMISSION1_27_0_
2007-01-05 12:58:35,277 DEBUG [org.hibernate.loader.Loader] result row: EntityKey[model.security.Permission#2]
2007-01-05 12:58:35,277 DEBUG [org.hibernate.type.LongType] returning '23601' as column: CHANNELID1_
2007-01-05 12:58:35,277 DEBUG [org.hibernate.loader.Loader] found row of collection: [model.aws.AwsChannel.permissionSet#23601]
2007-01-05 12:58:35,277 DEBUG [org.hibernate.engine.CollectionLoadContext] reading row
2007-01-05 12:58:35,277 DEBUG [org.hibernate.type.StringType] returning '6074c07f0d36c010VgnVCM100000f932a8c0____' as column: GUID1_
2007-01-05 12:58:35,277 DEBUG [org.hibernate.jdbc.AbstractBatcher] about to close ResultSet (open ResultSets: 1, globally: 1)
2007-01-05 12:58:35,277 DEBUG [org.hibernate.jdbc.AbstractBatcher] about to close PreparedStatement (open PreparedStatements: 1, globally: 1)
2007-01-05 12:58:35,277 DEBUG [org.hibernate.jdbc.AbstractBatcher] closing statement
2007-01-05 12:58:35,277 WARN  [ui.widget.plugin.AbstractWidget] processOutput(): could not get channel information for widget. Clearing contents to prevent faulty display.
java.lang.NullPointerException
   at org.hibernate.persister.entity.AbstractEntityPersister.loadByUniqueKey(AbstractEntityPersister.java:1596)
   at org.hibernate.type.EntityType.loadByUniqueKey(EntityType.java:608)
   at org.hibernate.type.EntityType.resolve(EntityType.java:382)
   at org.hibernate.type.EntityType.nullSafeGet(EntityType.java:204)
   at org.hibernate.persister.collection.AbstractCollectionPersister.readElement(AbstractCollectionPersister.java:703)
   at org.hibernate.collection.PersistentSet.readFrom(PersistentSet.java:318)
   at org.hibernate.loader.Loader.readCollectionElement(Loader.java:994)
   at org.hibernate.loader.Loader.readCollectionElements(Loader.java:634)
   at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:579)
   at org.hibernate.loader.Loader.doQuery(Loader.java:689)
   at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:224)
   at org.hibernate.loader.Loader.loadCollection(Loader.java:1985)
   at org.hibernate.loader.collection.CollectionLoader.initialize(CollectionLoader.java:36)
   at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:565)
   at org.hibernate.event.def.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:60)
   at org.hibernate.impl.SessionImpl.initializeCollection(SessionImpl.java:1716)
   at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:344)
   at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:86)
   at org.hibernate.collection.PersistentSet.iterator(PersistentSet.java:163)

batmat · **Posted:** Fri Jan 05, 2007 5:35 pm

merkkila wrote:

Code:

<set name="permissionSet" table="TBLCHANNELCONTENTMAPPING" where="guid in (select a.guid from bnp_permissions a)">
            <key column="CHANNELID" />
             <many-to-many column="GUID" property-ref="guid" not-found="ignore" class="model.security.Permission" />
</set>

I can't see why you've such error.

Maybe try temporarily removing the where and table attributes on your set, and maybe also property-ref and not-found on the many-to-many. This way, you can see if the problem goes away and reduce the fields of possibilites :-).

my 2 cents...

mamana · **Joined:** Tue May 30, 2006 1:33 pm **Posts:** 5

Problem remains in 3.3.1.GA

Debbuging Hibernate's code I found that the AbstractEntityPersister tries to use an "static key loader" from the map "uniqueKeyLoaders" which is always empty, hence -> NPE (line 1681)

There is some logic in the "getAppropriateUniqueKeyLoader" and we can make it not to create it's own "uniqueKeyLoader" and avoid NPE.

The result ends being a clean workaround and worked for the webapp we are building.

For some reason, if there is a filter enabled in the session, it will not use the "static key loader" and will create one. For that reason, I created a dummy Filter and enabled it. The filter does nothing, it's just there to make an "if condition" false.

the hbm for the parent must have the filter for the many-to-many relation like this:

Code:

      <map name="positionDetailDatesMap" table="so_owner.op_voyage_positions" mutable="false" inverse="true" >
         <key>
            <column name="company_id"></column>
            <column name="ship_id"></column>
            <column name="voyage_no"></column>
         </key>
         <map-key type="long" formula="key_position"></map-key>
         <many-to-many class="com.osg.chops.shipboard.domain.PositionDetailsDates" property-ref="keyPosition" order-by="arr_datetime asc" not-found="ignore">
            <formula>key_position</formula>
         </many-to-many>
         <filter name="myFilter" condition="1=1"></filter>
      </map>

Also, in the same file, somewhere at the end declare the filter

Code:

   <filter-def name="myFilter">

   </filter-def>

The final blow to it is to enable the filter for the current session.

Code:

currentSession.enableFilter("myFilter");

In my case I have a request filter and we use one session per request, so I make sure to run thi code on every request.

I'd love to know what the problem may be. This is just a workaround and Im not sure in deep how this affect hibernate behavior, performance, etc.

Can someone please bring more light on this?
bye bye
Dj

mac24nz · **Joined:** Tue Apr 27, 2010 5:18 pm **Posts:** 19

Hi.

I had the same problem and the solution / work around it still working fine in Hibernate 3.6

Thanks for posting the solution.
It seems like Hibernate is a little weaker when not using the primary key, rather a natural id

Martin