Red Hat Summit Red Hat SummitSupportConsoleDéveloppeursCommencer un essaiContact

Ce contenu n'est pas disponible dans la langue sélectionnée.

8.4. Components as composite identifiers

You can use a component as an identifier of an entity class. Your component class must satisfy certain requirements:
  • It must implement java.io.Serializable.
  • It must re-implement equals() and hashCode() consistently with the database's notion of composite key equality.

Note

In Hibernate3, although the second requirement is not an absolutely hard requirement of Hibernate, it is recommended.
You cannot use an IdentifierGenerator to generate composite keys. Instead the application must assign its own identifiers.
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. 
<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>
Copy to Clipboard Toggle word wrap
Any foreign keys referencing the OrderLine table are now composite. Declare this in your mappings for other classes. An association to OrderLine is mapped like this: 
<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>
Copy to Clipboard Toggle word wrap

Note

The <column> tag is an alternative to the column attribute everywhere.
A many-to-many association to OrderLine also uses the composite foreign key: 
<set name="undeliveredOrderLines">
    <key column name="warehouseId"/>
    <many-to-many class="OrderLine">
        <column name="lineId"/>
        <column name="orderId"/>
        <column name="customerId"/>
    </many-to-many>
</set>
Copy to Clipboard Toggle word wrap
The collection of OrderLines in Order would use: 
<set name="orderLines" inverse="true">
    <key>
        <column name="orderId"/>
        <column name="customerId"/>
    </key>
    <one-to-many class="OrderLine"/>
</set>
Copy to Clipboard Toggle word wrap
The <one-to-many> element declares no columns.
If OrderLine itself owns a collection, it also has a composite foreign key. 
<class name="OrderLine">
    ....
    ....
    <list name="deliveryAttempts">
        <key>   <!-- a collection inherits the composite key type -->
            <column name="lineId"/>
            <column name="orderId"/>
            <column name="customerId"/>
        </key>
        <list-index column="attemptId" base="1"/>
        <composite-element class="DeliveryAttempt">
            ...
        </composite-element>
    </set>
</class>
Copy to Clipboard Toggle word wrap
Retour au début
Red Hat logoGithubredditYoutubeTwitter

Apprendre

Essayez, achetez et vendez

Communautés

À propos de la documentation Red Hat

Nous aidons les utilisateurs de Red Hat à innover et à atteindre leurs objectifs grâce à nos produits et services avec un contenu auquel ils peuvent faire confiance. Découvrez nos récentes mises à jour.

Rendre l’open source plus inclusif

Red Hat s'engage à remplacer le langage problématique dans notre code, notre documentation et nos propriétés Web. Pour plus de détails, consultez le Blog Red Hat.

À propos de Red Hat

Nous proposons des solutions renforcées qui facilitent le travail des entreprises sur plusieurs plates-formes et environnements, du centre de données central à la périphérie du réseau.

Theme

© 2025 Red Hat