Unable to map foreign key to a composite key in Hibernate

ravi_shan · **Joined:** Fri Nov 18, 2005 5:09 am **Posts:** 1

Hi,

I am facing a peculiar situation where i have 2 fields(each as a foreign key) in a table and in the associated table these 2 fields together form a composite key(PK).
So i when i map each of these foreign keys to individual keys, i get the same error.
"
Initial SessionFactory creation failed.org.hibernate.MappingException: Foreign key (FKDF4D06517F636367:FileInstance [FileWatchRunId]))
must have same number of columns as the referenced primary key (FileWatchRun [FileWatchRunId,FileWatchDefinitionId])
"
Here are the mappings for ready reference.

====== Mappings for the composite key ======

<hibernate-mapping>
<class name="com.test.WatchRun" table="WatchRun">
<composite-id >
<key-property name="WatchRunId" column="WatchRunId" />
<key-many-to-one name="DefinitionId" class="com.test.Definition" column="DefinitionId" />
</composite-id>
</class>
</hibernate-mapping>

====== For the foreign key mapping ===============

<class name="com.test.Instance" table="Instance">
<id name="instanceId" column="InstanceId">
<generator class="increment"/>
</id>
<many-to-one name="WatchRunId" class="com.test.WatchRun" column="WatchRunId" not-null="true"/>
<many-to-one name="DefinitionId" class="com.test.Definition" column="DefinitionId" not-null="true"/>
</class>

A prompt response will be greatly appreciated.
Thanks,
============================

nathanmoon · **Posted:** Fri Nov 18, 2005 11:33 am

The docs explain how to do this here:

http://www.hibernate.org/hib_docs/v3/reference/en/html_single/#components-compositeid

Here's a quote from the docs:

Quote:

Use the <composite-id> tag (with nested <key-property> elements) in place of the usual <id> declaration. For example, the OrderLine class has a primary key that depends upon the (composite) primary key of Order.

Code:

<class name="OrderLine">
    
    <composite-id name="id" class="OrderLineId">
        <key-property name="lineId"/>
        <key-property name="orderId"/>
        <key-property name="customerId"/>
    </composite-id>
    
    <property name="name"/>
    
    <many-to-one name="order" class="Order"
            insert="false" update="false">
        <column name="orderId"/>
        <column name="customerId"/>
    </many-to-one>
    ....
    
</class>

Quote:

Now, any foreign keys referencing the OrderLine table are also composite. You must declare this in your mappings for other classes. An association to OrderLine would be mapped like this:

Code:

<many-to-one name="orderLine" class="OrderLine">
<!-- the "class" attribute is optional, as usual -->
    <column name="lineId"/>
    <column name="orderId"/>
    <column name="customerId"/>
</many-to-one>

Quote:

(Note that the <column> tag is an alternative to the column attribute everywhere.)