From: Peter Bailey <pbailey@...>
Date: 2007-09-25T05:01:00+09:00
Subject: Re: getting XPath in REXML to dive deeper

Gavin Kistner wrote:
> Peter Bailey wrote:
>> I'm finally using REXML instead of plain vanilla Ruby to convert XML
>> data. I've learned a bit about XPath and how REXML can use it. I've got
>> a sample XML file whose root element is <registration>. Underneath that
>> element are a bunch of children elements. So, when I do the instruction
>> listed below, I get all of them. But, I don't get the last two elements
>> that, to me anyway, are children, too. The only thing different about
>> them is that they have children, too. Does anyone know the nomenclature
>> for getting ALL of the children of an element, not just those that are
>> immediate children. I guess I want grandkids, too!
>> 
>> XPath.each(doc, "//registration/*") { |element| puts element.text }
> 
> The term you are looking for is 'descendants'. In XPath, '/' is 
> shorthand for the 'child' axis. You want the 'descendant' axis, which 
> has the shorthand (that you already used) of '//'.
> 
> So "//registration//*" is "At any level, find an element named 
> 'registration', and then find every element below any of them."
> 
> You possible want "registration//*" which is "every element in the 
> entire XML file at every level except for the root node", but that seems 
> rather pointless. (Why have a hierarchy in the XML if you're throwing 
> away the meaning?) Perhaps that will work for you, or perhaps you should 
> think further about exactly what elements you really want to traverse.
> 
> Hope that helps (oh, and this has nothing to do with Ruby, BTW :p)
> Gavin

Yes, this helps. Thanks, Gavin. What I did, to get everything I needed 
was this:

XPath.each(doc, "//registration//*") { |element| puts element.text }

I just put in a second "/" after registration. That picked up ALL of the 
descendants, and the grand-child elements, or, whatever they're called. 
My only problem is that the output is kind of spacey, with a lot more 
white space before those grand-child elements.   -Peter
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