XSLT with RSS feeds - html

Question

I have an RSS feed that changes regularly (same format, different data) and I need to apply a transform to it to get a list of items from it using tags. The problem is, I never know what position the item with the correct tags will be in. Example: If I was generating a carousel from this for a page that is related to "theory" I'd need to pull the "items" from the list of items in the RSS that have the relevant tags, then append the class "active" to the element with the class "newsitem row item".
I realize I could do this extremely easily with jQuery -- >
$(".newsitem.row.item").first().attr("class","newsitem row item active");
But, if possible, I'd like to save a step and generate the HTML with the active class in place.
<rss xmlns:atom=" ... " version="2.0">
<channel>
<title>Latest News</title>
<link>http://...</link>
<description>Latest News</description>
<atom:link href="..." rel="self"/>
<language>en</language>
<copyright>Copyright (c) 2015</copyright>
<lastBuildDate>Sat, 25 Apr 2015 23:39:40 -0500</lastBuildDate>
<item>
<title>TITLE FOR FIRST ITEM</title>
<link>LINK FOR FIRST ITEM</link>
<description>DESCRIPTION</description>
<pubDate>Sat, 25 Apr 2015 23:39:40 -0500</pubDate>
<guid>GUID</guid>
<category>gallery</category>
<category>events</category>
<item>
<title>TITLE FOR NEXT ITEM</title>
<link>LINK FOR NEXT ITEM</link>
<description>DESCRIPTION ...</description>
<pubDate>Tue, 10 Mar 2015 20:59:12 -0500</pubDate>
<guid>GUID ...</guid>
<category>architecture</category>
<category>class acts</category>
<category>competitions</category>
<category>feature</category>
<category>global college</category>
<category>graduate work</category>
<category>health systems & design</category>
<category>honors</category>
<category>rss</category>
<category>wellness</category>
</item>
...
<item>
<title>TITLE FOR THE NTH ITEM</title>
<link>LINK FOR THE NTH ITEM</link>
<description>DESCRIPTION ...</description>
<pubDate>Tue, 10 Mar 2015 20:52:45 -0500</pubDate>
<guid>GUID ...</guid>
<category>applied creativity</category>
<category>gallery</category>
<category>coa gallery</category>
<category>graduate work</category>
<category>research</category>
<category>rss</category>
<category>technology</category>
<category>theory-philosophy</category>
<category>video</category>
<category>visualization</category>
</item>
</channel>
</rss>
My code is:
<xsl:stylesheet xmlns:xsl="..." version="1.0">
<xsl:template match="/">
<div class="row">
<div class="col-md-12 banner_image vanish">
<div class="carousel newsitems slide" data-carousel-delay="8000" id="banner-latest-85695">
<div class="carousel-inner">
<xsl:apply-templates select="//item"/>
</div>
<a class="carousel-control left" data-slide="next" href="#banner-latest-85695" title="Previous News Item"></a>
<a class="carousel-control right" data-slide="next" href="#banner-latest-85695" title="Next News Item"></a>
</div>
</div>
</div>
</xsl:template>
<xsl:template match="item|text()">
<xsl:if test="category[contains(text(),'theory')]">
<div class="newsitem row item">
<xsl:if test="position() = ?"> <!-- what position test do I use? -->
<xsl:attribute name="class">newsitem row item active</xsl:attribute>
</xsl:if>
<div class="image span">
<img>
<xsl:attribute name="src">
<xsl:value-of select="carousel"/>
</xsl:attribute>
<xsl:attribute name="alt">
<xsl:value-of select="title"/>
</xsl:attribute>
</img>
</div>
<div class="details span">
<h2>
<a>
<xsl:attribute name="href">
<xsl:value-of select="link"/>
</xsl:attribute>
<xsl:value-of select="title"/>
</a>
</h2>
<div class="publication-date">
<span>posted</span>
<xsl:value-of select="pubDate"/>
</div>
<div class="description">
<xsl:value-of select="description"/>
</div>
</div>
</div>
</xsl:if>
</xsl:template>
This works if the first item in the rss feed contains the tag I am looking for. What am I overlooking here?
** EDITED TO CLARIFY
LINKS REPLACED WITH "..."

Answer 1

Your question is not entirely clear. If you want to select item (or items) by the "tag" it contains, you should do something like:
XSLT 1.0
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:template match="/">
<div>
<xsl:apply-templates select="rss/channel/item[tag2]"/>
</div>
</xsl:template>
<xsl:template match="item">
<div>
<span>
<xsl:value-of select="value"/>
</span>
</div>
</xsl:template>
</xsl:stylesheet>
Here, we're looking for item/s with a child element named tag2. Applying this to the following test input:
<rss>
<channel>
<item>
<tag1/>
<value>100</value>
</item>
<item>
<tag2/>
<value>200</value>
</item>
<item>
<tag2/>
<value>201</value>
</item>
<item>
<tag3/>
<value>300</value>
</item>
</channel>
</rss>
produces the result:
<?xml version="1.0" encoding="UTF-8"?>
<div>
<div>
<span>200</span>
</div>
<div>
<span>201</span>
</div>
</div>