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Support for primary key generation outside of the entity bean is available through custom implementations of the entity creation command objects used to insert entities into a persistent store. The list of available commands is specified in entity-commands element of the jbosscmp-jdbc.xml
descriptor. The default entity-command
may be specified in the jbosscmp-jdbc.xml
in defaults element. Each entity element can override the entity-command
in defaults by specifying its own entity-command
. The content model of the entity-commands
and child elements is given below.
Each entity-command
element specifies an entity generation implementation. The name
attribute specifies a name that allows the command defined in an entity-commands
section to be referenced in the defaults and entity elements. The class
attribute specifies the implementation of the org.jboss.ejb.plugins.cmp.jdbc
. JDBCCreateEntityCommand
that supports the key generation. Database vendor specific commands typically subclass the org.jboss.ejb.plugins.cmp.jdbc
. JDBCIdentityColumnCreateCommand
if the database generates the primary key as a side effect of doing an insert, or the org.jboss.ejb.plugins.cmp.jdbc.JDBCInsertPKCreateCommand
if the command must insert the generated key.
The optional attribute
element(s) allows for the specification of arbitrary name/value property pairs that will be available to the entity command implementation class. The attribute
element has a required name
attribute that specifies the name property, and the attribute
element content is the value of the property. The attribute values are accessible through the org.jboss.ejb.plugins.cmp.jdbc.metadata.JDBCEntityCommandMetaData.getAttribute
(String) method.