com.googlecode.objectify.annotation

Annotation Type Subclass

@Retention(value=RUNTIME)
@Target(value=TYPE)
public @interface Subclass

Indicates that a class is part of a polymorphic persistence hierarchy. Subclasses of an @Entity should be flagged with this annotation.

This is used for Objectify's implementation of polymorphism. Place this on any class in an inheritance hierarchy that should be queryable except the root. For example, in the hierarchy Animal->Mammal->Cat, annotations should be:

• @Entity Animal
• @EntitySubclass(index=true) Mammal
• @EntitySubclass(index=true) Cat

The @Entity annotation must be present on the class that identifies the root of the hierarchy. This class will define the kind of the entire hierarchy. The @Entity annotation must NOT be present on any subclasses.

Actual Java subclasses are not required to have @EntitySubclass, but only Java classes which have @EntitySubclass can be persisted and queried for. Note that subclass discriminators are not indexed by default, so if you want to query for specific types of subclasses, use @EntitySubclass(index=true).

Author:

Jeff Schnitzer

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
String[]	alsoLoad Additional discriminators which, when encountered, will be interpreted as indicating this subclass.
boolean	index If true, the discriminator will be indexed, and a query for the specific subclass will return results.
String	name Optionally define the discriminator value for the subclass; default is Class.getSimpleName()

Element Detail

name

public abstract String name

Optionally define the discriminator value for the subclass; default is Class.getSimpleName()

Default:

""

index

public abstract boolean index

If true, the discriminator will be indexed, and a query for the specific subclass will return results. However, superclasses and further subclasses may be have different index states.

This is NOT the same as putting @Index on a class; that sets the default index state of the fields of that class. This attribute only controls indexing of the discriminator.

Default:

false

alsoLoad

public abstract String[] alsoLoad

Additional discriminators which, when encountered, will be interpreted as indicating this subclass. Facilitates schema changes in a way analagous to @AlsoLoad.

Default:

{}