HermannSW

Yesterday I got asked by a colleague why DataPower XSLT processor complained about

"Illegal Pattern: Axis parent is illegal, only child and attribute are allowed"
when using a parent step in a XPath expression.

 

I created a simple sample and did not get the error.
The problem to solve is to act on the <CustomField>'s <Value> child who's <Name> child has a specific value only.

This is a simple sample data.xml:

 

Here is the simple stylesheet I created first:

 

As can be seen the correct <Value> just gets extracted from data.xml:

 

OK, so parent step ("..") is  not allowed by the spec, but I needed to provide a working solution to my colleague.

The trick is not to match on the <Name> element of interest first, that is already too deep.
Instead matching on the common predecessor (parent) of <Name> and <Value>, <CustomField> and
reformulating the XPath expression does solve the problem, see solution.xsl:

 

 

You can see here that everything works fine with the modified match pattern:
Hermann_{<myXsltBlog/> <myXsltTweets/>}