• Lifecycle Method Annotations
• Examples
• Simple @PrePersist
• EntityListerners
• No Delete Support

Lifecycle Method Annotations

There are various annotations which can be used to register callbacks on certain lifecycle events. These include Pre/Post-Persist (Save), and Pre/Post-Load.

• @PrePersist - Called before save, it can return a DBObject in place of an empty one.
• @PostPersist - Called after the save call to the datastore
• @PreLoad - Called before mapping the datastore object to the entity (POJO); the DBObject is passed as an argument (you can add/remove/change values)
• @PostLoad - Called after mapping to the entity

See the AllAnnotation for a full list of the annotations supported.

Examples

Here is a one of the test classes: http://code.google.com/p/morphia/source/browse/trunk/morphia/src/test/java/com/google/code/morphia/TestDatastore.java#82

All parameters and return values are options in your implemented methods.

Simple @PrePersist

Here is a simple example of an entity that always saves the Date it was last updated at.

class BankAccount {
  @Id String id;
  Date lastUpdated = new Date();

  @PrePersist void prePersist() {lastUpdated = new Date();}
}

EntityListerners

In addition, you can separate the lifecycle event implementation in an external class, or many.

@EntityListeners(BackAccountWatcher.class)
class BankAccount {
  @Id String id;
  Date lastUpdated = new Date();
}

class BankAccountWatcher{
  
  @PrePersist void prePersist(BankAccount act) {act.lastUpdated = new Date();}

}

No Delete Support

Because deletes are usually done with queries there is no way to support a Delete lifecycle event. If, or when, server-side triggers are enabled there may be some support for this, but even then it will be hard to imagine how this would logically fit.