Parsing xml using xslt fails when adding namespace to xml

I have the following xml file:

<DataConfiguration 
  xmlns="http://www.mysite.com/namespace"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.mysite.com/namespace/DataConfiguration.xsd">

  <rule>
    <if>
       ...
    </if>
    <then>
       ...
    </then>
  </rule>

</DataConfiguration>

which I want to parse using the following xslt:

<xsl:stylesheet 
  version="1.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:xsi="http://www.w3开发者_开发知识库.org/2001/XMLSchema-instance"
  xmlns:doc="http://www.mysite.com/namespace" 
  exclude-result-prefixes="xsi">

<xsl:output omit-xml-declaration="yes"/>
<xsl:output method="text"/>
<xsl:template match = "/">

<xsl:for-each select="//rule">
  <xsl:for-each select="if/*">
     ...
  </xsl:for-each>
</xsl:for-each>

</xsl:template>
</xsl:stylesheet>

The xslt works as expected but when I add the xmlns attribute to the top element of the xml it fails to find the xml elements. I saw some related questions on this site but still didn't figure out how to solve my specific problem. I tried to add doc: to the select as suggested here but it didn't help. Maybe it's because I'm using // ? Any other way to do these queries ?

Any other suggestion how to solve this ?

---

This is the biggest XPath XSLT FAQ. Just search: "XPath default namespace"

Very briefly:

Change:

<xsl:for-each select="//rule">   
  <xsl:for-each select="if/*">   
     ...   
  </xsl:for-each>   
</xsl:for-each> 

To:

<xsl:for-each select="//doc:rule">   
  <xsl:for-each select="doc:if/*">   
     ...   
  </xsl:for-each>   
</xsl:for-each> 

The reason for the observed confusing problem is that in XPath any unprefixed name is considered to be in "no namespace".

Therefore, select="//rule" doesn't select any element in a document that is in a default namespace -- there is no element named rule that is in no namespace.

Instead, the XPath expression must contain prefixed names and the prefix must be associated with the default namespace -- as done in the above solution.