# Rexml and some rather basic problems **URL:** \ **Category:** Ruby\ **Created:** [January 11, 2008, 11:55am UTC](https://www.ruby-forum.com/t/rexml-and-some-rather-basic-problems/125712 "2008-01-11T11:55:55Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![lasastard](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/58956e/32.png) [@lasastard](https://www.ruby-forum.com/u/lasastard)\ **Post date:** [January 11, 2008, 11:55am UTC](https://www.ruby-forum.com/t/rexml-and-some-rather-basic-problems/125712/1 "2008-01-11T11:55:55Z")
Hi, I’ve been playing around with ruby for a while now, but wouldnt consider myself an experienced user. For a new project I want to use a xml parser to extract some information from a file. I understand that rexml is the tool of choice and that it has various options to actually perform this task (tree, stream parsing). My question concerns how to access multiple children of an element at one go… I guess that requires some explanation: This is, in principle, how the xml source looks like ... ... ... ... ... and so on. In reality, we are dealing with a file that holds information about genes, their name, their location and some other features. Each gene needs to be dealt with individually (e.g. iterating) as I have some methods that need to be applied to each entry or rather some of its features. What I cant figure out is thus: How do I get the entry (I figure its Element.elements.each(‘entry’)) and then in the same “go” also some, not all, of its children. These children are at different levels, too. If I use Elements.elements.each(‘entry’), the whole entry gets stored as one element in an array. That on its own is not a big problem, but at that point I havent even touched on the children yet. If I try to further treat them as if I was dealing with XML code (i.e. filter for elements) it wont work. But isnt there a way other than normal array methods and simple text parsing to get the children? Most, if not all the tutorials I found were specifically focusing on attributes after filtering on the “primary” level, which is no good to me since I dont have any attributes in my xml file (although having those would make thinks much easier…). Or in other words: How can I filter for an entry and then puts (or store in a variable) some of its children like ‘puts Element.elements.each(‘entry’) do {|output| puts output(’//feature1’, ‘//feature2’)}’. The last bit is obviously nonsense, but in principle what I am looking for. Anyhow, I hope someone understands what I am trying to say here and can point me in the right direction 🙂 Cheers, Marc ---
**Author:** ![lasastard](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/58956e/32.png) [@lasastard](https://www.ruby-forum.com/u/lasastard)\ **Post date:** [January 11, 2008, 12:45pm UTC](https://www.ruby-forum.com/t/rexml-and-some-rather-basic-problems/125712/2 "2008-01-11T12:45:42Z")
> Cheers, > Marc > Hi Marc, There are multiple ways to go about what you appear to be asking for, but the main ambiguity in your question is why do you want to select the target elements all “in one go”? If this is an absolute requirement, perhaps you could explain the rationale behind it a bit more. If it is _not_ a requirement, then you can simply write an event- based parser (one approach) and then store only the information that interests you in a “placeholder” or “bookkeeping” variable. If there are multiple subsets of information that you want to extract, then just save those multiple subsets into multiple variables, or save them into multiple attributes of a single “bookkeeping object” that converts the XML into a native ruby object. Probably the best way to illustrate is by way of example code. Here’s a sample link: [http://www.janvereecken.com/2007/4/11/event-driven-xml-parser-in-ruby](http://www.janvereecken.com/2007/4/11/event-driven-xml-parser-in-ruby) HTH ---
**Author:** ![lasastard](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/58956e/32.png) [@lasastard](https://www.ruby-forum.com/u/lasastard)\ **Post date:** [January 11, 2008, 1:17pm UTC](https://www.ruby-forum.com/t/rexml-and-some-rather-basic-problems/125712/3 "2008-01-11T13:17:27Z")
Thanks for the link! What I did, after some sweat and tears and so on is the following: After storing all instances of the element in an array (Element.elements.each) I created a new document via Document.new and used a string as input that I created from the array. Like so: Element.elements.each(’//entry’) do |solution| eachentry = Document.new solution.to\_s ``` eachentry.elements.each('feature1') {|somemethod| print ``` somemethod.text} … end Probably far from elegant, but it actually does what I need. Concerning why I need this in one go is because I am creating some additional information from the actual entries which, among other things, use a counter that has to be resetted for each entry (1, 2, 3 and so on). Anyhow, thanks again! /Marc