# Validating characters before libxml processing

**URL:** <https://www.ruby-forum.com/t/validating-characters-before-libxml-processing/151622>\
**Category:** Ruby\
**Created:** [October 23, 2008, 3:35pm UTC](https://www.ruby-forum.com/t/validating-characters-before-libxml-processing/151622 "2008-10-23T15:35:49Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![michaelb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/b19c9b/32.png) [@michaelb](https://www.ruby-forum.com/u/michaelb)\
**Post date:** [October 23, 2008, 3:35pm UTC](https://www.ruby-forum.com/t/validating-characters-before-libxml-processing/151622/1 "2008-10-23T15:35:49Z")

</div>

I have a Ruby/Rails script which receives data passed into it as a param  
in xml format. This data is packaged up “remotely” and I don’t have any  
control over what it can contain other than that the contents of the  
elements have had their html entities encoded into text. The problem  
I’m having is that libxml is choking on some characters. The particular  
instance that brought the problem to my attention is a string which  
contains the ♂ character (ascii 11).

I have been searching around and found several sites which seem to  
address the problem but none seem to do the “whole job”. I can strip  
this specific character out obviously but given that libxml must have a  
clearly defined set of valid characters it can handle, how do I process  
that string before passing it to libxml to guarantee that it does not  
contain any characters that libxml can’t process without overdoing it?