RS and XSLT, pt1: Applying a Basic Transformation
February 22, 2008
It was driving me nuts — my transforms just wouldn't apply. I tried working with some fake data, from my little-used O'Reilly XML in a Nutshell, and that worked fine. So why couldn't I transform my Reporting Services output? After banging my head against this one for a while, I finally decided to mess around with the root <Report ... /> node, first by removing all the extra elements (because my samples did not have any elements in the root node). Voilà, the transform now works. Why is that?
Continuing with the trial-and-error approach, I discovered that it was the "xmlns" attribute causing the problem. I looked that up and found that it is a namespace. Suddenly everything became clear, since I'm quite used to namespaces in imperative programming languages like C#, but had not seen it before in declarative languages.
Back to O'Reilly and the section on XSLT and Namespaces, and I see that you can add other namespaces to the <xsl:stylesheet ...> element with ease. All I needed to do was synch up the reporting services output with my stylesheet.
Root element in Reporting Services output
<Report p1:schemaLocation="XmlTest http://reportserver?%2fXmlTest&rs%3aFormat=XML&rc%3aSchema=True" Name="XmlTest" xmlns:p1="http://www.w3.org/2001/XMLSchema-instance" xmlns="XmlTest">Original stylesheet root node:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">Proper stylesheet root node:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:rpt="XmlTest">
Now in the transform I just have to use the assigned prefix, rpt, when matching the Report element: <xsl:template match="rpt:Report">.
Update 2/28
As I'll explain again in a future post, Reporting Services seems to skip the namespace when you apply the transformation file in the "Data transform" property of the "Data Output" tab. That is, if no transformation is specified in the report, the resulting XML will have the namespace. If the transformation is specified, then your transformation should assume that Reporting Services will not use the namespace. Clear as mud?