From: Robert Klemme <shortcutter@...>
Date: 2007-08-31T06:20:04+09:00
Subject: Re: REXML Element exists question

On 30.08.2007 11:35, John Butler wrote:
> An xml file is generated and i am currently parsing through it in a
> rails app.  The problem with this XML file is sometimes the elelment
> doesnt have a value it sometimes doesnt include the tags in the file.
> So for example:
> 
> If it has a value
> <Client>Client Name</Client>
> 
> An empty value
> <Client></Client>
> 
> Sometimes i wont even have the above tags depending on how the file was
> generated from a different application.
> 
> I want to check if the Client element is present in the file so the
> following code below works somehow:

This should do what you need:

doc = REXML::Document.new(File.read(f))
cl = REXML::XPath.first(doc, '//Client')
project.client = cl.text if cl

> if !element.elements["Client"].nil?
>     project.client = element.elements["Client"].text
> end
> 
> My question is there a more elegant way to this?  I dont want to have to
> write an if/case statment for every possible element.  I did try the
> below but that gave me an error on the nil? because it couldnt find the
> element to test if it was nil, thats why im suprised the above code
> works.
> 
> !element.elements["Client"].nil ? project.client =
> element.elements["Client"].text : project.client = nil
> 
> 
> I have looked at the rexml docs for elements, attributes but nothing
> works if the <client></client> tags are not present.

IMHO the REXML tutorial is great source:
http://www.germane-software.com/software/rexml/docs/tutorial.html

I also often look at
http://www.w3schools.com/xpath/
http://www.zvon.org/xxl/XPathTutorial/General/examples.html

Kind regards

	robert