Convert meters to foot in xml data via xsl transformation

Question

I would like to modify my xml file by converting some values (tag@v) from meter to foot. I am a newbie to xml and this should be no problem for one of you. The formular is: 1 meter are 3.2808 feet I want to convert the attribute value of node/tag@v if node/tag@k="ele". Can anyone post me the whole xsl? Thank you in advance.

<?xml version="1.0" encoding="utf-8"?>
<osm version="0.6">
    <bounds minlat="47.8760339819708" minlon="13.5747679669094" maxlat="48.0521802776284" maxlon="14.0487569652016" origin="OSMXAPI" />

    <node id="756570510" uid="-1" lat="47.9728596" lon="13.6008265">
        <tag k="amenity" v="parking" />
        <tag k="wheelchair" v="yes" />
    </node>
    <node id="756570534" uid="-1" lat="47.9728043" lon="13.6003445" />
    <node id="766968743" uid="-1" lat="47.914342" lon="13.9834639" />
    <node id="766972197" uid="-1" lat="47.9163063" lon="14.006467">
        <tag k="fixme" v="Lage" />
        <tag k="name" v="Hobelsberg" />
        <tag k="natural" v="peak" />
    </node>
    <node id="766972201" uid="-1" lat="47.9168672" lon="14.0181185">
        <tag k="ele" v="947" />
        <tag k="fixme" v="Lage" />
        <tag k="name" v="Kaiserkogel" />
        <tag k="natural" v="peak" />
    </node>
    <node id="766972204" uid="-1" lat="47.9155297" lon="14.0451337">
        <tag k="ele" v="1080" />
        <tag k="fixme" v="Lage" />
        <tag k="name" v="Pernecker Kogel" />
        <tag k="natural" v="peak" />
        <tag k="summit:cross" v="yes" />
    </node>
</osm>

My goal is to get a xml file with the computed "tag@v" values like:

<?xml version="1.0" encoding="utf-8"?>
<osm version="0.6">
    <bounds minlat="47.8760339819708" minlon="13.5747679669094" maxlat="48.0521802776284" maxlon="14.0487569652016" origin="OSMXAPI" />

    <node id="756570510" uid="-1" lat="47.9728596" lon="13.6008265">
        <tag k="amenity" v="parking" />
        <tag k="wheelchair" v="yes" />
    </node>
    <node id="756570534" uid="-1" lat="47.9728043" lon="13.6003445" />
    <node id="766968743" uid="-1" lat="47.914342" lon="13.9834639" />
    <node id="766972197" uid="-1" lat="47.9163063" lon="14.006467">
        <tag k="fixme" v="Lage" />
        <tag k="name" v="Hobelsberg" />
        <tag k="natural" v="peak" />
    </node>
    <node id="766972201" uid="-1" lat="47.9168672" lon="14.0181185">
        <tag k="ele" v="3107" />
        <tag k="fixme" v="Lage" />
        <tag k="name" v="Kaiserkogel" />
        <tag k="natural" v="peak" />
    </node>
    <node id="766972204" uid="-1" lat="47.9155297" lon="14.0451337">
        <tag k="ele" v="3543" />
        <tag k="fixme" v="Lage" />
        <tag k="name" v="Pernecker Kogel" />
        <tag k="natural" v="peak" />
        <tag k="summit:cross" v="yes" />
    </node>
</osm>

I've startet a xslt but i don't no how to make it correct.

<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
    <xsl:output method="xml" encoding="UTF-8" indent="yes"/>

        <xsl:template match="/">

        <osm>
            <xsl:copy-of select="osm/bounds"/>

            <xsl:for-each select="//node">


                <node><xsl:value-of select="node"/></node>

                <xsl:for-each select="/tag">                
                    <xsl:choose>
                        <xsl:when test="contains(@k,'ele')">
                            <xsl:value-of select="round(v*3.2808)"/>
                        </xsl:when>
                        <xsl:otherwise>
                            <xsl:value-of select="tag"/>
                        </xsl:otherwise>
                    </xsl:choose>             
                </xsl:for-each>                

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

    </xsl:stylesheet>

Answer 1

There are several issues with your approach. For example, instead of:

<node><xsl:value-of select="node"/></node>

which creates empty node elements (because your node elements are empty), you should be using something like:

<node><xsl:copy-of select="@*"/></node>

and instead of:

<xsl:for-each select="/tag"> 

which selects nothing, because tag is not a child of the / root node, you should be selecting the tag elements that are children of the current node:

<xsl:for-each select="./tag">   

which can be shortened to:

<xsl:for-each select="tag"> 

However, instead of continuing down this path, I would suggest you adopt a better overall strategy: use the identity transform template to copy all nodes as the rule, then add a template matching the attribute you want to modify as the exception:

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:strip-space elements="*"/>

<!-- identity transform -->
<xsl:template match="@*|node()">
    <xsl:copy>
        <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
</xsl:template>

<xsl:template match="tag[@k='ele']/@v">
    <xsl:attribute name="v">
        <xsl:value-of select="round(. * 3.28084)" />
    </xsl:attribute>
</xsl:template>

</xsl:stylesheet>