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Re: [aspectj-users] How to create "conditional ITDs"?
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Hi Matthew,
I've done that to introduce @Id and @Version if not provided on JPA
classes. You need to use the -XhasMember compiler option, and then I
wrote it this way :
public aspect InstallIdByDefault {
/**
* Marker interface for beans receiving the default id.
*
* @author Simone Gianni <simoneg@xxxxxxxxxx>
*/
public static interface WithDefaultId {
}
declare parents : ((@Entity *) && !(@NoId *) && !hasmethod(@(Id||EmbeddedId) public * get*()) && !hasfield(@(Id||EmbeddedId) * *)) implements WithDefaultId;
/**
* The default provided id field.
*/
private long WithDefaultId.id;
/**
* Getter for the default id.
* @return The entity id.
*/
@Id
@GeneratedValue
public long WithDefaultId.getId() {
return id;
}
/**
* Setter for the default id.
* @param newId The entity id.
*/
void WithDefaultId.setId(long newId) {
id = newId;
}
}
You can find the complete aspects (also for @Version) here : http://svn.apache.org/repos/asf/labs/magma/trunk/database-jpa/src/main/java/org/apache/magma/database/openjpa/
Simone
Matthew Adams wrote:
Hi all,
I was wondering how it might be possible to achieve what I'm calling a
conditional inter-type declaration.
Here's a simple auditing example. For a JPA entity, I want to
introduce a @PrePersist method if and only if the target class doesn't
have one because it's an error to have multiple @PrePersist methods on
an entity. If it already has a @PrePersist method, I want to execute
advice after the target instance's @PrePersist method is invoked by
the JPA implementation. Same for @PreUpdate.
The example below will work for Person, but not for Document --
Document will end up with two @PrePersist methods. How can I refactor
this to work for both?
========
@Entity
public class Document {
// ...
@PrePersist
private void prePersist() { /* ... */ }
}
========
@Entity
public class Person {
// ...
}
========
// works only for an @Entity that DOES NOT define a @PrePersist or a
@PreUpdate method
public aspect AuditingItd {
private interface Auditable {
}
declare parents: (@javax.persistence.Entity *) implements Auditable;
@Column(name = "updated")
private Date Auditable.updated;
@PrePersist
private void Auditable.auditablePrePersist() {
updated = new Date();
}
@PreUpdate
private void Auditable.auditablePreUpdate() {
updated = new Date();
}
}
=========
-matthew
--
Simone Gianni CEO Semeru s.r.l. Apache Committer
http://www.simonegianni.it/
