Question

I have a table in SQL Server 2000 with a text field containing XML that I need to display on a C# ASP.NET 2.0 page. I need to retrieve the XML and then filter out a list of about 80 possible elements (or white list 20 possible elements to keep might be better).

I can pull the xml out of the DB and display it on my .aspx page, but I am not sure how to filter out any elements first.

Example XML

<Message> 
  <MessageNumber>
    1234
  </MessageNumber> 
  <MessageType>
    Auto Notice
  </MessageType> 
  <UPMessageNumber>
    5501
  </UPMessageNumber> 
  <MessageID>
    121223
  </MessageID> 
  <ResponseTo>
    654321
  </ResponseTo>
  <DateTime>
    2010-11-10 09:35:00
  </DateTime>
</Message> 

In this case I will need to filter out the UPMessageNumber and MessageID before displaying it on the page.

Thanks for any ideas.

Answer 1

You can do this using XSLT to transform input XML into a modified output.

C# example here.

This step-by-step article shows you
how to apply an Extensible Stylesheet
Language (XSL) Transformation (XSLT)
to an Extensible Markup Language (XML)
document by using the XslTransform
class to create a new XML document.
XSL is an XML-based language that is
designed to transform one XML document
into another XML document or an XML
document into any other structured
document.

The previous question here addresses directly how to construct XSL for element stripping.

I think the XSL you need is:

<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
  <xsl:output method="xml"/>

  <xsl:template match="@*|node()" priority="10">
    <xsl:copy>
      <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
  </xsl:template>

  <xsl:template match="UPMessageNumber | MessageID" priority="20">
  </xsl:template>

</xsl:stylesheet>

The first xsl:template copies all nodes by default. The second omits the named elements.