Self-reference entity in Hibernate

Question

Hi guys,

I have an Action entity, that can have other Action objects as child in a bidirectional one-to-many relationship. The problem is that Hibernate outputs the following exception:

"Repeated column in mapping for collection: DbAction.childs column: actionId"

Below the code of the mapping:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
 "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"&gt;
<hibernate-mapping>
 <class name="DbAction" table="actions">

  <id name="actionId" type="short" />
  <property not-null="true" name="value" type="string" />

  <set name="childs" table="action_action" cascade="all-delete-orphan">
   <key column="actionId" />
   <many-to-many column="actionId" unique="true" class="DbAction" />
  </set>

  <join table="action_action" inverse="true" optional="false">
   <key column="actionId" />
   <many-to-one name="parentAction" column="actionId" not-null="true" class="DbAction" />
  </join>
 </class>
</hibernate-mapping>

Answer 1

That's because you have name="actionId" declared more than once for the same table.

Answer 2

As armandino suggested, i tried to substitute the column name to "parentActionId", and it works:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
 "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"&gt;
<hibernate-mapping>
 <class name="DbAction" table="actions">

  <id name="actionId" type="short" />
  <property not-null="true" name="value" type="string" />

  <set name="childs" table="action_action" cascade="all-delete-orphan">
   <key column="parentActionId" />
   <many-to-many column="actionId" unique="true" class="DbAction" />
  </set>

  <join table="action_action" inverse="true" optional="false">
   <key column="actionId" />
   <many-to-one name="parentAction" column="parentActionId" not-null="true" class="DbAction" />
  </join>
 </class>
</hibernate-mapping>