dear guys,

I am using Hibernate 3.0.5, and there's many-to-many relation between Item and Tag object,

there's also one-to-many between Game and Tag.

the hibernate .hbm.xml fragment is as below:

Game.hbm.xml
<set name="tags" lazy="true" cascade="all" order-by="ITEM_INDEX asc">
<key column="GAME_ID"/>
<one-to-many class="com.domain.Tag" />
</set>

Item.hbm.xml
<set name="tags" lazy="true" table="ITEM_TAG">
<key column="ITEM_ID"/>
<many-to-many column="TAG_ID" class="com.domain.Tag" />
</set>


tag.hbm.xml
<property name="tagName" column="TAG_NAME" not-null="true" />
<property name="itemType" column="ITEM_TYPE" not-null="true" />
<property name="itemIndex" column="ITEM_INDEX" type="integer" not-null="false" />
<property name="gameId" column="GAME_ID" type="long" update="false" not-null="true" />

in the program, we add new tag to persistent game first, then add the tag to item.

nomally, it works well, the sql statement is below(we just add one new Item at one time):
[LOGGER] 2007-04-25 09:47:06 DEBUG org.hibernate.SQL | insert into tag (TAG_NAME, ITEM_TYPE, ITEM_INDEX, GAME_ID, TAG_ID) values (?, ?, ?, ?, ?)
[LOGGER] 2007-04-25 09:47:06 DEBUG org.hibernate.SQL | insert into ITEM (STATUS, GSC_ID, GSC_HOLDING_ID, ITEMNAME, ITEMTYPE, ITEMQTY, ITEMPROPERTY, bundle_id, OWNER_ID, SALELISTING_ID, BELONGED_GAME_ACCOUNT, TRANSFER_GAME_TARGET, BRIEFDESCRIPTION, LOCK_DATE, WITHDRAW_DATE, salable_type, ITEM_ID) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 'ITEM', ?)
[LOGGER] 2007-04-25 09:47:06 DEBUG org.hibernate.SQL | update tag set GAME_ID=? where TAG_ID=?
[LOGGER] 2007-04-25 09:47:06 DEBUG org.hibernate.SQL | insert into ITEM_TAG (ITEM_ID, TAG_ID) values (?, ?)

sometimes the hibernate will generate the sql below(we add many new Items at one time):

[LOGGER] 2007-04-25 09:47:06 DEBUG org.hibernate.SQL | insert into ITEM (STATUS, GSC_ID, GSC_HOLDING_ID, ITEMNAME, ITEMTYPE, ITEMQTY, ITEMPROPERTY, bundle_id, OWNER_ID, SALELISTING_ID, BELONGED_GAME_ACCOUNT, TRANSFER_GAME_TARGET, BRIEFDESCRIPTION, LOCK_DATE, WITHDRAW_DATE, salable_type, ITEM_ID) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 'ITEM', ?)
[LOGGER] 2007-04-25 09:47:06 DEBUG org.hibernate.SQL | insert into tag (TAG_NAME, ITEM_TYPE, ITEM_INDEX, GAME_ID, TAG_ID) values (?, ?, ?, ?, ?)
[LOGGER] 2007-04-25 09:47:06 DEBUG org.hibernate.SQL | insert into tag (TAG_NAME, ITEM_TYPE, ITEM_INDEX, GAME_ID, TAG_ID) values (?, ?, ?, ?, ?)
[LOGGER] 2007-04-25 09:47:06 DEBUG org.hibernate.SQL | update tag set GAME_ID=null where GAME_ID=? and TAG_ID=?

the last sql statement will trigger the database exception,because the constraint on gamd_id,and also this statement is wired.

any suggestions?

HI Battlefly,


update this

Item.hbm.xml

<set name="tags" lazy="true" cascade="all" order-by="ITEM_INDEX asc" inverse="true">
<key column="GAME_ID"/>
<one-to-many class="com.domain.Tag" />
</set>

and in
tag.hbm.xml

<property name="gameId" column="GAME_ID" type="long" update="false" insert="false" not-null="true" />

if I do as you said, then the relation table item_tag is gone, and the many-to-many relation between Item and Tag will disappear.

What I want to know is why Hibernate generate the sql as that, why it will update tag table with null game_id?

Hi Battlefly,

It is because of inverse mapping. If you set inverse =true then Hibernate will not do like this. If you use Bidirectional mapping with inverse true .It would generate less SQL update.Thses are Synchronization step with session mapped persistent inverse false object.

you might get more idea on

http://simoes.org/docs/hibernate-2.1/155.html under
Second Let's have a look at a relationship update Heading

seems that make TAG in GAME inverse can work, thanks for replying.