jpa-for-scala's Introduction

JPAExtension

JPA

JSR 317: JavaTM Persistence 2.0 (JPA 2.0) is s a POJO persistence API for object/relational mapping. It contains a full object/relational mapping specification supporting the use of Java language metadata annotations (and/or XML descriptors) to define the mapping between Java objects and a relational database.

The definition of persistent entities, relations, interceptors etc. is annotation based (if you do not use the XML descriptors). Only dependent from the standard package javax.persistence . This allows to choose different JPA implementations/providers like:

All of them do provide additional rich feature enhancements like PostGIS syntax, compile time entity enhancement, plug-able extensibility etc.

JPAExtension

JPAExtension does provide

a Scala interface to the base JPA classes EntityManager, EntityMangerFactory, Query etc. to ease their usage
Transaction scope and query wrapper to mesh better with Scala’s FP
more type safe interface using Scala’s type system
externalized query and filter class definition (dedicated XML file)
Query parameter holder classes for type safe binding

I know that the most challenging thing is to provide working Scala implementations (suitable for Java Reflection API’s expectations). I will try to collect as many examples as possible for the common issues. (If you have one, contact me.)

The JPAExtension is available at Scala-Tools Maven Snapshot Repository
and it will be available at the Snapshot Documentation Site soon.

For now please visit the short blogposts (blog.fakod.eu/tag/jpa/ ) I wrote to get an impression of JPAExtension and Scala entities.

And as usual: Follow me on Twitter

Maven

To use JPAExtension simple put the following dependency in your pom.xml

	</dependencies>
	  <dependency>
	    <groupId>org.scala-libs</groupId>
	    <artifactId>jpaextension</artifactId>
	    <version>0.0.2-SNAPSHOT</version>
	  </dependency>
	</dependencies>