SimpleDS provides a simple persistence framework for Google AppEngine
that gets as little in the way as possible. It is barely a wrapper
around Datastore APIs, providing mapping between Entity and Java
classes.
This version includes small modifications to existing features and
some new ones:
Maven and javadoc
=================
This release includes a maven artifact and online javadoc [1].
Transactions
============
We are now supporting transactions [2] as included in GAE:
try {
Transaction tx = entityManager.beginTransaction();
entityManager.put(tx, instance);
tx.commit();
} catch (RuntimeException e) {
tx.rollback();
throw e;
}
Since this is cumbersome, we are also including a @Transactional
annotation and aspect interceptor (thanks to John Patterson for
pointing out a much simpler implementation):
@Transactional(noRollbackFor=MailException.class)
public void save(FooBar foobar, Baz baz) {
entityManager.put(entityManager.beginTransaction(),
ImmutableList.of(foobar, baz));
mailService.sendConfirmation("Operation completed
successfully");
}
PagedQuery
==========
There is a new PagedQuery.transform() method that uses the Google
Collections API [3]:
PagedQuery query = entityManager.createPagedQuery(UserData.class):
PagedList<UserData> list = entityManager.findPaged(query);
PagedList<String> userNames = list.transform(new Function<UserData,
String> {
public String apply(UserData from) {
return from.getName();
}
});
Spring JavaConfig example
=========================
We have added an example using Spring JavaConfig [1] instead of Spring
XML. A Guice example would nice to have, if anyone would like to step
up to it :)
Next on the roadmap: @Cacheable and schema migration.
Best regards,
Nacho.
[1] http://code.google.com/p/simpleds/wiki/GettingStarted
[2] http://code.google.com/p/simpleds/wiki/Transactions
[3] http://code.google.com/p/simpleds/wiki/PagedQuery
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