Vitor Rodrigues » mapping

Persisting XML with OpenJPA

vitor — Tue, 23 Oct 2007 18:15:46 +0000

I’ve been looking at JPA – Java Persistence Architecture and decided to play a bit with OpenJPA using DB2 as the back-end. My goal: to persist and query XML data in DB2, making use of DB2′s pureXML capabilities to query the XML data using SQL/XML‘s XMLQUERY() function.

However, while OpenJPA has an extensive documentation, the examples are not always complete and there isn’t a lot of information on the web regarding OpenJPA error determination and solving. So, here are some recommendations for some of the problems I have encountered. The class xml.Address is the one to be persisted as XML in the database using JPA and it is stored as the field shipAddress of the Order objects.

 [java] Exception in thread "main" 
org.apache.openjpa.persistence.ArgumentException:
Type "class xml.Address" does not have persistence metadata.

Suggestion: Remove the reference to xml.Address from persistence.xml.

[java] Exception in thread "main" 
org.apache.openjpa.persistence.InvalidStateException:
Encountered unmanaged object "xml.Address@9b2a51" in
persistent field "xml.Order.shipAddress" of managed object "xml.Order@12b3349"
during flush.  However, this field does not allow cascade persist. 
You cannot flush unmanaged objects.
  [java] FailedObject: xml.Address@9b2a51

Suggestion: Make sure you have no @Entity or @Embeddable annotations in xml.Address. The main annotation is @XmlRootElement.

 [java] Exception in thread "main" 
org.apache.openjpa.persistence.PersistenceException:
"xml" doesnt contain ObjectFactory.class or jaxb.index

Suggestion: add a file jaxb.index into your xml package containing all the classes to be persisted as XML: a file containing Address in our case.

DB2 on Rails update

vitor — Wed, 17 Oct 2007 20:45:35 +0000

I’m back to fiddling around with my Ruby on Rails experiments(1)(2). I was able to create a very useful 2-way mapping between Ruby objects and xml data stored in DB2 pureXML. Basically, trying to replicate some of ActiveRecord’s functionality but for XML data. I still find it odd, though, that both ROXML and xml-mapping haven’t had much activity as of late. I’m wondering if there is any new OXM library around that I don’t know of.

Also on the same topic:

the main DB2 on Rails website is up and running again, with a revamped design and now using wordpress instead of typo.
a new version of the ibm_db driver was also released, containing several bugfixes. Update it through gems (gem update ibm_db) or from here: http://rubyforge.org/projects/rubyibm/

XML Mapping in Ruby

vitor — Thu, 05 Jul 2007 16:34:07 +0000

Dear lazy web…

I’ve been playing with Ruby and XML lately, and one of the key features I need to use is XML mapping from XML to Ruby objects and vice versa. However, both ROXML and XML::Mapping do not seem to be very active at the moment. Both forums contain un-replied questions several months old, and I can’t find any examples that are not a couple of years old.

Is there any XML Mapping library for Ruby that is currently active(*)? XML::Mapping was serving me good enough, until the moment that I needed some of the documented features and found that they are not supported in the current release

(*) by active I don’t mean it needs to be in exclusively in code development, but at least with some recent activity in forums, documentation, examples, etc..