creating many-to-many relationship ...

gubrak · **Joined:** Tue Mar 20, 2007 5:13 am **Posts:** 9

hi, i have problem trying to create a many-to-many relationship.

i have 2 classes:

Code:

public class Venue {
   private Integer venueId;
   private String venueType;
   private String venueName;
   private Set Club;

  // getter & setter
  // add & remove Club

Code:

public class Club{
   private Integer clubId;
   private String clubName;
   private Set Venue

  // getter & setter, add & remove

my hbm file is as follow
Venue.hbm.xml

Code:

...
        <set name="venueClubRelationship" table="club_venue" cascade="save-update">
            <key column="venueId"/>
            <many-to-many class="Club"/>
        </set>
...

Club.hbm.xml

Code:

...
        <set name="clubVenueRelationship" table="club_venue" cascade="save-update">
            <key column="clubId"/>
            <many-to-many class="Venue"/>
        </set>
...

when i try to test this code by running this following code:

Code:

...
Club club= (Club)new ClubDAO().getClubById(1);
Venue v = (Venue)new VenueDAO().getVenueById(7);
club.addVenue(v);
boolean success = new ClubDAO().save(club);
System.out.println("success: " + success);
...

it gives me this error:

Code:

   at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:103)
   at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:91)
   at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
   at org.hibernate.persister.collection.AbstractCollectionPersister.insertRows(AbstractCollectionPersister.java:1394)
   at org.hibernate.action.CollectionUpdateAction.execute(CollectionUpdateAction.java:56)
   at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:248)
   at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:232)
   at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:142)
   at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:298)
   at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
   at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000)
   at com.jjcs.fas.dbms.organisation.OrganisationDAO.save(OrganisationDAO.java:172)
   at com.jjcs.fas.dbms.organisation.Test_OrganisationDAO.<init>(Test_OrganisationDAO.java:43)
   at com.jjcs.fas.dbms.organisation.Test_OrganisationDAO.main(Test_OrganisationDAO.java:22)
Caused by: java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC][SQLServer]Cannot insert the value NULL into column 'venueId', table 'DB_DBMS.dbo.club_venue'; column does not allow nulls. INSERT fails.
   at com.microsoft.jdbc.base.BaseExceptions.createException(Unknown Source)
   at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source)
   at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processErrorToken(Unknown Source)
   at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReplyToken(Unknown Source)
   at com.microsoft.jdbc.sqlserver.tds.TDSRPCRequest.processReplyToken(Unknown Source)
   at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReply(Unknown Source)
   at com.microsoft.jdbc.sqlserver.SQLServerImplStatement.getNextResultType(Unknown Source)
   at com.microsoft.jdbc.base.BaseStatement.commonTransitionToState(Unknown Source)
   at com.microsoft.jdbc.base.BaseStatement.postImplExecute(Unknown Source)
   at com.microsoft.jdbc.base.BasePreparedStatement.postImplExecute(Unknown Source)
   at com.microsoft.jdbc.base.BaseStatement.commonExecute(Unknown Source)
   at com.microsoft.jdbc.base.BaseStatement.executeUpdateInternal(Unknown Source)
   at com.microsoft.jdbc.base.BasePreparedStatement.executeUpdate(Unknown Source)
   at org.hibernate.jdbc.NonBatchingBatcher.addToBatch(NonBatchingBatcher.java:23)
   at org.hibernate.persister.collection.AbstractCollectionPersister.insertRows(AbstractCollectionPersister.java:1367)
   ... 10 more

how should i handle this?
I know the problem is because the field is not set as "allow-null" but how should I do that?

Could someone please explain me how should I fix this issue?

Thank you very much![/code]

gubrak · **Joined:** Tue Mar 20, 2007 5:13 am **Posts:** 9

no idea for this one?

dharmendra.pandey · **Posted:** Mon May 21, 2007 11:18 pm

Hi gubrak,

In both HBM set you are referring same table. Dose it make sense

<set name="venueClubRelationship" table="club_venue" cascade="save-update">
<key column="venueId"/>
<many-to-many class="Club"/>
</set>

<set name="clubVenueRelationship" table="club_venue" cascade="save-update">
<key column="clubId"/>
<many-to-many class="Venue"/>
</set>

kuzhali · **Posted:** Tue May 29, 2007 12:08 am

Hi,

I think you need to have same column name to map both the tables.

kakaroto · **Joined:** Tue May 29, 2007 12:33 am **Posts:** 13

The way I see it, you have a many-to-many association but are not specifying which side is the owner and which is the inverse. In such situations, hibernate needs to know which side of the association it will use to perform the inserts, updates, .., etc.

Check this out:
http://www.hibernate.org/hib_docs/v3/re ... irectional

Then, in Venue.hbm.xml, change

Code:

<set name="venueClubRelationship" table="club_venue" cascade="save-update">
            <key column="venueId"/>
            <many-to-many class="Club"/>
        </set>

for

Code:

<set name="venueClubRelationship" table="club_venue" cascade="save-update" inverse="true">
            <key column="venueId"/>
            <many-to-many class="Club"/>
        </set>

Cheers!!!