[jira] [Updated] (JDO-764) Allow JDO annotations to be used in meta-annotations

["Craig L Russell (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/JDO-764?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Craig L Russell updated JDO-764:
--------------------------------
    Attachment: jdo-764.patch

> Allow JDO annotations to be used in meta-annotations
> ----------------------------------------------------
>
>                 Key: JDO-764
>                 URL: https://issues.apache.org/jira/browse/JDO-764
>             Project: JDO
>          Issue Type: Improvement
>          Components: api, specification
>    Affects Versions: JDO 3.1
>            Reporter: Andy Jefferson
>             Fix For: JDO 3.2
>
>         Attachments: jdo-764.patch, JDO-764.patch
>
>
> By default annotations are used directly in a persistable class. Java additionally allows annotations to be formed of other annotations. This is particularly useful where a user has a particular combination of annotations to set on a class/field/method and wants to simply annotate with an abbreviated form. For example, specifying attributes of an annotation
> @PersistenceCapable(detachable="true", identityType="datastore", embeddedOnly="true")
> or formed of multiple annotations
> @PersistenceCapable(detachable="true")
> @Extension(vendorName="datanucleus", key="multitenancy-column-name", value="TENANT")
> These can be represented as meta-annotations like this
> @Target(TYPE)
> @Retention(RUNTIME)
> @PersistenceCapable(detachable="true", identityType="datastore", embeddedOnly="true")
> public @interface DatastoreIdPersistable
> {
> }
> @Target(TYPE)
> @Retention(RUNTIME)
> @PersistenceCapable(detachable="true")
> @Extension(vendorName="datanucleus", key="multitenancy-column-name", value="TENANT")
> public @interface MultitenantPersistable
> {
> }
> and the user can subsequently just annotate their persistable class as
> @DatastoreIdPersistable
> public class MyClass1 {...}
> @MultitenantPersistable
> public class MyClass2 {...}
> The work required to support this in the JDO spec is simply to update the following annotations to add @Target({ElementType.ANNOTATION_TYPE})
> The annotations requiring this are
> @Element, @EmbeddedId, @Key, @NotPersistent, @Order, @Persistent, @Serialized, @Transactional, and @Value  (all other annotations already have @Target({ElementType.TYPE}) which already permits their usage in meta-annotations.
> The same is proposed for JPA 2.2, see https://github.com/javaee/jpa-spec/issues/43



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