sorting | Dmytro Shteflyuk's Home https://kpumuk.info In my blog I'll try to describe about interesting technologies, my discovery in IT and some useful things about programming. Mon, 07 Sep 2015 23:41:12 +0000 en-US hourly 1 https://wordpress.org/?v=6.7.1 Sorting RSS-feed by date using XSLT https://kpumuk.info/development/sorting-rss-feed-by-date-using-xslt/ https://kpumuk.info/development/sorting-rss-feed-by-date-using-xslt/#comments Thu, 06 Apr 2006 06:22:15 +0000 http://kpumuk.info/xslt/sorting-rss-feed-by-date-using-xslt/ In my previous post I’ve described how to display RSS-feed in browser using XSLT. But sometimes It’s necessary to change order of items in feed, for example sort them by date. XSLT 1.1 allows sorting by complex data types, but XSLT 1.0 does not and we need extract separate date parts. First I want to […]

The post Sorting RSS-feed by date using XSLT first appeared on Dmytro Shteflyuk's Home.]]> In my previous post I’ve described how to display RSS-feed in browser using XSLT. But sometimes It’s necessary to change order of items in feed, for example sort them by date. XSLT 1.1 allows sorting by complex data types, but XSLT 1.0 does not and we need extract separate date parts.

First I want to demonstrate simplicity of sorting by date in XSLT 1.1. We need just define dc namespace:

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<xsl:stylesheet version="1.1"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:digg="http://digg.com//docs/diggrss/"
  xmlns:dc="http://purl.org/dc/elements/1.1/">

Now we are ready to sort:

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<xsl:apply-templates select="item">
  <xsl:sort select="pubDate" data-type="dc:date" order="ascending"/>
</xsl:apply-templates>

As I said early in XSLT 1.0 we need to split date to get day, month and so on. To convert month to number I will use following XML-tree:

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  <months:months>
    <name>Jan</name>
    <name>Feb</name>
    <name>Mar</name>
    <name>Apr</name>
    <name>May</name>
    <name>Jun</name>
    <name>Jul</name>
    <name>Aug</name>
    <name>Sep</name>
    <name>Oct</name>
    <name>Nov</name>
    <name>Dec</name>
  </months:months>

It’s time to create sorting code:

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<xsl:variable name="vMonths" select="document('')/*/months:*"/>
<xsl:apply-templates select="item">
  <xsl:sort select="substring(substring-after(substring-after(substring-after(pubDate, ' '), ' '), ' '), 1, 4)" order="ascending"/>
  <xsl:sort select="count($vMonths/name[
                  .=substring(substring-after(substring-after(current()/pubDate, ' '), ' '), 1, 3)]
                  /preceding-sibling::name)"
            data-type="number"
            order="ascending"/>
  <xsl:sort select="substring(substring-after(pubDate, ' '), 1, 2)" data-type="number" order="ascending"/>
  <xsl:sort select="substring(substring-after(substring-after(substring-after(substring-after(pubDate, ' '), ' '), ' '), ' '), 1, 8)" data-type="text" order="ascending"/>
</xsl:apply-templates>

That’s all. Feed items will be sorted by date in ascending order.

You can view results here or download full sources here.

Books recommended

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