[JCR-977] jcr:deref and parent axis in xpath predicates

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0-alpha4
• Component/s: jackrabbit-core, jackrabbit-spi-commons, query
• Environment: n/a
• Assignee: Marcel Reutegger
• Reporter: Frederic Esnault
• Created: 22/Jun/07 09:39
• Updated: 02/Nov/09 14:27
• Resolved: 10/Jul/09 11:54

Description

Currently, the jcr:deref() function is not allowed in a xpath query predicate. Example :
book holds a reference property on its author(s)
authors have a name

We want all books from a specific author :

/jcr:root/element(*, bookType)[jcr:deref(@author, 'authorType')/@name = 'King']

This fails with an InvalidQueryException currently (not supported).

The error is raised in the XPathQueryBuilder class, in function : private QueryNode createFunction(SimpleNode node, QueryNode queryNode), in the block :
else if (NameFormat.format(JCR_DEREF, resolver).equals(fName))

Problem is that with this query, when evaluating the jcr:deref() function, then in this method at this point, queryNode.getType() is 0 and tests raise the exception if queryNode.getType() is neither QueryNode.TYPE_LOCATION nor QueryNode.TYPE_PATH.

I think this is a useful place to put a deref function in a query, as I don't know how we could test the referenced node properties another way.

Frederic Esnault

Issue Links

• is duplicated by: JCR-1659 Support parent axis inside Xpath predicates