XSL woes - mike's web log/comments

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December 27, 2007 | XSL woes | 1230 hit(s)

One of the problems with using a technology like XSLT only when you need to is that you never get much better, and every new task is a headache. I'm having a transform problem that's stumped me and for now I'm giving up. Maybe you can help.

I have all those quotations (see left, or all of them) in an XML file that looks like this (this is the beginning of the file):

<?xml version="1.0" standalone="yes"?>
<QuotationsTable>
  <Quotation>
    <quoteId>1</quoteId>
    <quote>And so to bed.</quote>
    <author>Samuel Pepys</author>
    <source />
    <tags>
      <tag>general</tag>
      <tag>literature</tag>
    </tags>
  </Quotation>
  <Quotation>
    <quoteId>2</quoteId>
    <quote>I have made this letter longer than usual, only 
        because I have not had the time to make it shorter.</quote>
    <author>Blaise Pascal</author>
    <source />
    <tags>
      <tag>writing</tag>
      <tag>editing</tag>
    </tags>
  </Quotation>
 
 <!-- etc. -->

I want to add tags, which as you can see I've added as a <tags> parent with individual <tag> child elements.

To display all of them, I have a page that uses an ASP.NET XmlDataSource control as the data source. A problem with using the XmlDataSource control is that it likes its data exposed as attributes, not elements. I sorted that out some time ago by creating an .xsl file that transformed the each quotation's child elements into attributes, like this:

<xsl:template match="/">
    <xsl:for-each select="QuotationsTable">
      
      <xsl:element name="Quotations">
        
        <xsl:for-each select="Quotation">
          <xsl:element name="Quotation">

            <xsl:attribute name="quoteId">
              <xsl:value-of select="quoteId"/>
            </xsl:attribute>
        
            <xsl:attribute name="quote">
              <xsl:value-of select="quote"/>
            </xsl:attribute>

            <xsl:attribute name="author">
              <xsl:value-of select="author"/>
            </xsl:attribute>
            
            <xsl:attribute name="source">
              <xsl:value-of select="source"/>
            </xsl:attribute>

          </xsl:element>
        </xsl:for-each>
      </xsl:element>
    </xsl:for-each>
  </xsl:template>

Now I want to add the tags. My current attempt looks like this ... I'm looping through the <tags> element and extracting each tag.

<!-- ... -->

<xsl:attribute name="source">
  <xsl:value-of select="source"/>
</xsl:attribute>

<xsl:attribute name="tags">
  <xsl:for-each select="tags/tag">
    <xsl:value-of select="tag" />&amp;nbsp;,
  </xsl:for-each>
</xsl:attribute >

<!-- etc. -->

This kind of works, for very loose definitions of "works". When I display the results, I see as many commas as I have tags for each quotation. But I don't see the actual tag values.

I'm stumped, and I don't know how one goes about debugging transforms, as I believe I've whined before. So I guess this will wait until I either am motivated to give it another bash or decide that XML is not the thing for this job. Which would be too bad, kinda.

Phil Weber 27 Dec 07 - 9:21 PM

Hi, Mike: Try this:


<xsl:attribute name="tags">
  <xsl:for-each select="tags/tag">
    <xsl:value-of select="."/>
    <xsl:if test="position()!=last()">, </xsl:if>
  </xsl:for-each>
</xsl:attribute >

mike 28 Dec 07 - 12:19 AM

Wow, Phil, that is so beautiful. Works like a charm. Looks like I needed different syntax for selecting the tag value, and the if test is just a bonus. :-)

Thanks!