Twig - Making the datastore more manageable

Twig is an object persistence interface built on Google App Engine's low-level datastore which overcomes many of JDO-GAEs limitations including improved support for inheritance, polymorphism and generic types. You can easily configure, modify or extend Twigs behaviour by implementing your own strategies or overriding extension points in pure Java code.

Twig is the only datastore interface to support: * Parallel Asynchronous Commands * Plain old Java object data models with no datastore dependencies * Merged OR queries on multiple properties

Read the documentation to get started

Visit the Twig Discussion Group to ask a question

Show me some code

The central interface you will use is ObjectDatastore which has an implementation AnnotationObjectDatastore

``` // create a new light-weight stateful datastore for every request ObjectDatastore datastore = new AnnotationObjectDatastore();

// create a complex object graph Band ledzep = createClassicRockband();

// store the instance and all other reachable instances Key key = datastore.store(ledzep);

// converted into a query by kind with a key name Band result = datastore.load(Band.class, "Led Zeppelin");

// the identical instance is always returned from same datastore assert result == ledzep;

// modernize the classic rock band ledzep.name = "White Stripes";

// call update on changed instances - no dirty detection datastore.update(ledzep);

// no need to deal with Keys
datastore.delete(ledzep);

// run a find command Iterator punkBands = datastore.find() .type(Band.class) .addFilter("genre", EQUAL, Genre.PUNK) .returnResultsNow(); ```

A common sentiment

Twig is named after the super thin sixties model Twiggy - or it could be something like Typesafe Wrapper in GAE