Hi Folks,

I have been struggling with this problem of creating a one-to-many bidirectional association on a join table.
I have a scenario where one DEVICE can be associated with many NODE's and the join table I use is DEVICE_NODE.

I am using hibernate tools to generate the code automatically and create the schema. On disabling the join in Device.hbm.xml, things work perfect and code is generated as per unidirectional one-to-many mapping with the creation of the DEVICE_NODE join table.
However if I leave the join portion uncommented(followed this example - http://docs.jboss.org/hibernate/core/3. ... l-join-12m), things fail with an exception which says -

org.hibernate.InvalidMappingException: Could not parse mapping document from resource Device.hbm.xml
Could not parse mapping document from resource Device.hbm.xml
org.hibernate.PropertyNotFoundException: field [node] not found on Device
field [node] not found on Device

Can someone let me know if am missing anything ?

Cheers n thanks
~v

Here are the hbm.xmls.

Device.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 29 Sep, 2010 10:54:52 AM by Hibernate Tools 3.3.0.GA -->
<hibernate-mapping>
<class name="Device" table="DEVICE" schema="PUBLIC" catalog="H2">
<id name="devId" type="java.lang.Long">
<column name="DEV_ID" />
<generator class="identity"></generator>
</id>
<property name="devType" type="string">
<column name="DEV_TYPE" length="30" not-null="true" />
</property>
<property name="desc" type="string">
<column name="DESC" length="30" />
</property>
<!-- bidirectional many-to-one - Always fails with the exception when uncommented >
<join table="DEVICE_NODE" inverse="true" optional="true">
<key column="DEV_ID"/>
<many-to-one name="node"
column="NODE_ID"
not-null="true"/>
</join-->
</class>
</hibernate-mapping>

Node.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 29 Sep, 2010 9:25:12 PM by Hibernate Tools 3.3.0.GA -->
<hibernate-mapping>
<class name="Node" table="NODE" schema="PUBLIC" catalog="H2">
<id name="nodeId" type="java.lang.Long">
<column name="NODE_ID" />
<generator class="identity"></generator>
</id>
<property name="desc" type="string">
<column name="DESC" length="30" />
</property>
<property name="location" type="string">
<column name="LOCATION" length="30" />
</property>
<set name="devices" table="DEVICE_NODE" inverse="false" lazy="true">
<key>
<column name="NODE_ID" not-null="true" />
</key>
<many-to-many entity-name="Node">
<column name="DEV_ID" not-null="true" unique="true" />
</many-to-many>
</set>
</class>
</hibernate-mapping>

Does your Device class have getNode()/setNode() methods?

Am trying to generate my classes from the hbm.xmls. So I dont have the classes yet.

thanks!

You'll need classes that matches the hbm.xml files. Otherwise Hibernate will not work.

Well, I am trying to generate my entity classes and schema ddl from the hbm.xmls using hibernate tools inside eclipse.
Once I get my classes generated(with annotations), I will throw away the xmls as they wont be needed anymore.

I havent got as far as running my hibernate program yet.

cheers!

Ok, I didn't notice that your question was about Hibernate Tools. Maybe you should post it in the Tools forum: viewforum.php?f=6

Sorry bout that, I shud have posted it in the right forum.

I have resolved this issue by eliminating the use of hbm.xml totally. I have used annotations and the bidirectional with join table works perfectly.

Here r the relevant portions of the entity class :

Device.java
>>>>
@ManyToOne(optional=true)
@JoinTable(name = "NODE_DEVICE",
joinColumns = {
@JoinColumn(name="DEV_ID")
},
inverseJoinColumns = {
@JoinColumn(name="NODE_ID")
}
)
public Node getNode() {
return node;
}
<<<<

Node.java
>>>>>
@OneToMany
@JoinTable(name = "NODE_DEVICE",
joinColumns = {
@JoinColumn(name="NODE_ID", unique = true)
},
inverseJoinColumns = {
@JoinColumn(name="DEV_ID")
}
)
public Set<Device> getDevices() {
return this.devices;
}
<<<<<

thnx again
Cheers!
~v

But the question now is, how will hibernate automatically add a tuple in the mapping table.
if I do a save(device) and save(node), will the row be automatically inserted in join table?

cheers!
~v