Hiding XSLT Tag Soup

July 21, 2008 - News - by - 4 Comments

The ever-interesting Jeff Atwood correctly points out that many frameworks force you to create tag soup – a horrible mess of executable code and HTML markup. Commenters suggest a number of solutions but none are really satisfying.

Our in-house framework started back in the bad old days with Java emitting HTML directly – surely the worst of all worlds. We figured out early on that it was better to create XML first, and transform with XSLT; for instance, this reduced the pain of generating reports from our screens, since we can transform the XML to flat files and PDFs.

However, even XSLT can be pretty soupy:


<xsl:choose>
  <xsl:when test="@current">
    <b><xsl:value-of select="@number"/></b>
  </xsl:when>
  <xsl:otherwise>
    <span style="cursor: hand;">
      <xsl:attribute name="onClick">
        <xsl:text>go('</xsl:text>
        <xsl:value-of select="@number"/>
        <xsl:text>');</xsl:text>
      </xsl:attribute>
      <u><xsl:value-of select="@number"/></u>
    </span>
  </xsl:otherwise>
</xsl:choose>


This implements page numbers with links to all but the current page, similar to Google’s Goooooooooogle:
1 2 3 4
Not only do we have lots of XSLT logic with smatterings of HTML thrown in, we even have some inline JavaScript at lines 8-10, which is code inside markup inside code!

We could clean up this particular example but it’s way too easy to create a mess like this. So we’ve gradually introduced more and more generic templates that take XML of a certain form and produce the corresponding HTML – including all the messy bits like JavaScript. For instance, here’s how we render a table of data with headings, column selection, and sorting:


<xsl:call-template name="chunk-multiple">
  <xsl:with-param name="node" select="data/content/section/dataset[@name='TABLE']"/>
</xsl:call-template>


Yes, it’s cheating because the template code is still tasty tag gumbo. But we have only a few templates, and we can concentrate on making them as readable as possible with comments and careful layout, while each individual application screen is defined in just one language – XSLT.

There’s a lot more cleaning up we could do with templates for our buttons and forms, but at least it’s more broth than chowder. Bon appétit!

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