Hi guys. This is only tangentially related to Hibernate, hope it's okay in the Miscellaneous section. I'm finding myself in need of a little expression language for selecting nodes in my object graph. Since my object graph happens to be a tree, I was thinking that xpath might make a good choice. I might be able to write a custom object model interface for Apache Commons JXPath or Jaxen and use them to interpret xpath expressions. If I was really clever, I might even be able to make it so that predicate expressions were implemented using collection filters. That would be really cool.

Has anyone else done anything similar? Anyone else use jaxen or jxpath for this? I hesitate to commit to one of those projects, since they've apparantly not seen active development in some time, but since the xpath spec has been final for quite some time, maybe that's a good thing.

Answering my own question, but hey, why not.

Turns out jxpath wasn't really doing it for me, but jaxen is a dream to work with, and this pattern is just absurdly useful in so many contexts. Now, given a node in my object tree, I can select other nodes and/or their values using lovely little xpath expressions, e.g.:



suitable for embedding in metadata, or run-time scripts written in javascript or python or whatever. The only thing I want now is the ability to implement predicate expression evaluation using hibernate filters so this stuff is super fast as well as crazy useful.

Has no one else ever experimented with this kind of thing?

Check that one http://www.ognl.org/
I used it successfully on a small project, I was a bit overkill however