31.4.3. Read-only Fields
JBoss allows for read-only CMP fields by setting the
read-only
and read-time-out
elements in the cmp-field
declaration. These elements work the same way as they do at the entity level. If a field is read-only, it will never be used in an INSERT
or UPDATE
statement. If a primary key field is read-only
, the create method will throw a CreateException
. If a set accessor is called for a read-only field, it throws an EJBException
. Read-only fields are useful for fields that are filled in by database triggers, such as last update. A read-only CMP field declaration example follows:
<jbosscmp-jdbc> <enterprise-beans> <entity> <ejb-name>GangsterEJB</ejb-name> <cmp-field> <field-name>lastUpdated</field-name> <read-only>true</read-only> <read-time-out>1000</read-time-out> </cmp-field> </entity> </enterprise-beans> </jbosscmp-jdbc>