The Secrets of GORM

GORM (the Grails Object/Relational Mapper) is one of the many high points of the Grails web framework. GORM is a thin Groovy wrapper over Hibernate, but that doesn't begin to capture excitement of what GORM brings to the party. Imagine being able to call book.save() and book.delete() on your Book class; calling Book.get(1) to retrieve your book from the database by primary key; using Book.list() to pull an ArrayList of Book objects into your application. Now imagine getting all of that functionality (and more) for free with each new class you define. No interfaces to implement. No abstract classes to extend. Persistence that is transparent, automatic, and simple to use: GORM. Querying your data via GORM is a case study in the benefits of using a dynamic language. Queries like Book.findByAuthorAndTitle(“Scott Davis”, “Groovy Recipes”) rule the day. For the really hard stuff, you can always get back to a more traditional SQL-based interface. We'll also explore Query-By-Example.

GORM allows you to model your objects in the database in a variety of ways. In addition to supporting the usual 1:M, 1:1, and M:M relationships, GORM allows you to flatten the model, breaking traditional normalization rules. (Just don't tell your DBAs about it…) Come see how GORM handles HashMaps, Arrays, and ArrayLists in your Groovy objects.

GORM can auto-generate your database schema from existing POGOs, but recognizes that not all development is greenfield development. GORM allows you to map existing tables to objects and arbitrary field names to POGO attributes. We'll also see how to bypass Hibernate altogether using EJB3 annotations.

If you are a Hibernate developer, you owe it to yourself to see how GORM makes a good thing even better. If you are a Groovy/Grails developer, come see how to get the most of your friendly neighborhood persistence framework.

About Scott Davis

Scott Davis is the founder of ThirstyHead.com, a training company that specializes in Groovy and Grails training.

Scott published one of the first public websites implemented in Grails in 2006 and has been actively working with the technology ever since. Author of the book Groovy Recipes: Greasing the Wheels of Java and two ongoing IBM developerWorks article series (Mastering Grails and in 2009, Practically Groovy), Scott writes extensively about how Groovy and Grails are the future of Java development.

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