Find and replace a string inside an image path - xslt

Question

I have a rss xml file that looks like below with the tag looping many times. I would like to replace the letter 's' with 'm' in the url inside the tag, So http://farm4.staticflickr.com/3802/9593294742_a38fca47c7_s.jpg becomes http://farm4.staticflickr.com/3802/9593294742_a38fca47c7_m.jpg
<rss xmlns:media="http://search.yahoo.com/mrss/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:creativeCommons="http://cyber.law.harvard.edu/rss/creativeCommonsRssModule.html" xmlns:flickr="urn:flickr:user" version="2.0">
<channel>
<title>CCGalleria Pool</title>
<link>http://www.flickr.com/groups/ccgalleria/pool/</link>
<item>
<title>Hampton Court Palace Gardens</title>
<link>http://www.flickr.com/photos/dksesh/9593294742/in/pool-1540822#N20</link>
<description>
<p>
dksesh
has added a photo to the pool:</p>
<p>
<a href="http://www.flickr.com/photos/dksesh/9593294742/" title="Hampton Court Palace Gardens">
<img src="http://farm4.staticflickr.com/3802/9593294742_a38fca47c7_m.jpg" width="240" height="107" alt="Hampton Court Palace Gardens"/>
</a>
</p>
</description>
<pubDate>Sun, 25 Aug 2013 10:33:09 -0700</pubDate>
<dc:date.Taken>2013-08-10T16:49:05-08:00</dc:date.Taken>
<author flickr:profile="http://www.flickr.com/people/dksesh/">nobody#flickr.com (dksesh)</author>
<guid isPermaLink="false">tag:flickr.com,2004:/grouppool/1540822#N20/photo/9593294742</guid>
<media:content url="http://farm4.staticflickr.com/3802/9593294742_a38fca47c7_b.jpg" type="image/jpeg" height="456" width="1024"/>
<media:title>Hampton Court Palace Gardens</media:title>
<media:thumbnail url="http://farm4.staticflickr.com/3802/9593294742_a38fca47c7_s.jpg" HEIGHT="75" WIDTH="75"/>
<media:credit ROLE="photographer">dksesh</media:credit>
<creativeCommons:license>http://creativecommons.org/licenses/by-nd/2.0/deed.en_GB</creativeCommons:license>
</item>
</channel>
</rss>
I have a code something like below, but didn't work. Can someone help? Thanks very much. Newly changed code below.
<?xml version='1.0'?>
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:media="http://search.yahoo.com/mrss/">
<xsl:output method="html" />
<xsl:template match="/">
<xsl:for-each select="rss/channel/item">
<xsl:variable name="newurl" select="replace(media:thumbnail/#url,'_s.jpg','_m.jpg')"/>
<img src="{$newurl}" style="margin:5px 5px" />
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>

Answer 1

Your stylesheet sample showns the version as "2.0" which is good, because there is a replace function you can use in XSLT 2.0 that will probably do the trick here
<xsl:variable name="newurl" select="replace(media:thumbnail/#url,'_s.jpg','_m.jpg')"/>
<img src="{$newurl}" style="margin:5px 5px" />
Note that the second argument of the replace function can actually be a regular expression, if you wanted more control over what 's' needed to be replaced.
As an aside, do note the correct use of Attribute Value Templates here, signified by the curly braces { }. You use them in outputting the src attribute of the img element, but not within the translate/replace function.
Here is the full XSLT in this case:
<xsl:stylesheet version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:media="http://search.yahoo.com/mrss/">
<xsl:output method="html" />
<xsl:template match="/">
<xsl:for-each select="rss/channel/item">
<xsl:variable name="newurl" select="replace(media:thumbnail/#url,'_s.jpg','_m.jpg')"/>
<img src="{$newurl}" style="margin:5px 5px" />
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>