com.dooapp.gaedo.extensions.migrable.Migrable Maven / Gradle / Ivy
package com.dooapp.gaedo.extensions.migrable;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* A migrable object supports association to a Migration class, that will allow data service to provide migration code, when stored object is not of the same version
* (as would have given the serialVersionUID field, as an example) of actually loaded class.
*
* Usage depends upon the FinderCrudService implementation but, in a general fashion, it should work as follow :
*
* at class laoding, this annotation is read, the storageVersion field is located, and the migratorClass is located.
* When an object is read from storage, if the value of its storageVersion field differs from the version given by migratorClass, the migrate method
* is called on data coming from storage (theorically before the object is loaded, but it is storage-dependant).
*
* @author ndx
*
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Migrable {
/**
* Class used for migration.
* @return
*/
Class migratorClass();
}