How to get a list of all used namespaces?
I'm writing an XSLT 1.0 stylesheet to transform multi-namespace XML documents to HTML. At some place in the result HTML I want to list all the namespaces, that occured in the document.
Is this possibile?
I thought about something like
<xsl:fo开发者_开发问答r-each select="//*|//@*">
<xsl:value-of select="namespace-uri(.)" />
</xsl:for-each>
but of course I'd get gazillions of duplicates. So I'd have to filter somehow, what I already printed.
Recursively calling templates would work, but I can't wrap my head around how to reach all elements.
Accessing //@xmlns:*
directly doesn't work, because one can't access this via XPath (one isn't allowed to bind any prefix to the xmlns:
namespace).
Another without extension functions:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="*">
<xsl:param name="pNamespaces" select="'
'"/>
<xsl:variable name="vNamespaces">
<xsl:variable name="vMyNamespaces">
<xsl:value-of select="$pNamespaces"/>
<xsl:for-each select="namespace::*
[not(contains(
$pNamespaces,
concat('
',.,'
')))]">
<xsl:value-of select="concat(.,'
')"/>
</xsl:for-each>
</xsl:variable>
<xsl:variable name="vChildsNamespaces">
<xsl:apply-templates select="*[1]">
<xsl:with-param name="pNamespaces"
select="$vMyNamespaces"/>
</xsl:apply-templates>
</xsl:variable>
<xsl:value-of select="concat(substring($vMyNamespaces,
1 div not(*)),
substring($vChildsNamespaces,
1 div boolean(*)))"/>
</xsl:variable>
<xsl:variable name="vFollowNamespaces">
<xsl:apply-templates select="following-sibling::*[1]">
<xsl:with-param name="pNamespaces" select="$vNamespaces"/>
</xsl:apply-templates>
</xsl:variable>
<xsl:value-of
select="concat(substring($vNamespaces,
1 div not(following-sibling::*)),
substring($vFollowNamespaces,
1 div boolean(following-sibling::*)))"/>
</xsl:template>
</xsl:stylesheet>
Output (With Dimitre's input sample):
http://www.w3.org/XML/1998/namespace
mynamespace
mynamespace2
mynamespace3
EDIT: Also this XPath expression:
//*/namespace::*[not(. = ../../namespace::*|preceding::*/namespace::*)]
As proof, this stylesheet:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text"/>
<xsl:template match="/">
<xsl:for-each select="//*/namespace::*
[not(. = ../../namespace::*|
preceding::*/namespace::*)]">
<xsl:value-of select="concat(.,'
')"/>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
Output:
http://www.w3.org/XML/1998/namespace
mynamespace
mynamespace2
mynamespace3
EDIT 4: Same efficient as two pass transformation.
This stylesheet:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text"/>
<xsl:key name="kElemByNSURI"
match="*[namespace::*[not(. = ../../namespace::*)]]"
use="namespace::*[not(. = ../../namespace::*)]"/>
<xsl:template match="/">
<xsl:for-each select=
"//namespace::*[not(. = ../../namespace::*)]
[count(..|key('kElemByNSURI',.)[1])=1]">
<xsl:value-of select="concat(.,'
')"/>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
Output:
http://www.w3.org/XML/1998/namespace
mynamespace
mynamespace2
mynamespace3
EDIT 5: When you are dealing with a XSLT processor without namespace
axe implementation (Like TransforMiix), you can only extract namespaces actually used with this stylesheet:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text"/>
<xsl:key name="kElemByNSURI" match="*|@*" use="namespace-uri()"/>
<xsl:template match="/">
<xsl:for-each select=
"(//*|//@*)[namespace-uri()!='']
[count(.|key('kElemByNSURI',namespace-uri())[1])=1]">
<xsl:value-of select="concat(namespace-uri(),'
')"/>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
TransforMiix output:
mynamespace2
This transformation:
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text"/>
<xsl:template match="/">
<xsl:for-each select=
"//namespace::*[not(. = ../../namespace::*)]">
<xsl:value-of select="concat(.,'
')"/>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
when applied on this XML document:
<authors xmlns:user="mynamespace">
<?ttt This is a PI ?>
<author xmlns:user2="mynamespace2">
<name idd="VH">Victor Hugo</name>
<user2:name idd="VH">Victor Hugo</user2:name>
<nationality xmlns:user3="mynamespace3">French</nationality>
</author>
</authors>
produces the wanted, correct result:
http://www.w3.org/XML/1998/namespace
mynamespace
mynamespace2
mynamespace3
Update:
As @svick has commented, the above solution will still occasionally produce duplicate namespaces such as with the following XML document:
<authors xmlns:user="mynamespace">
<?ttt This is a PI ?>
<author xmlns:user2="mynamespace2">
<name idd="VH">Victor Hugo</name>
<user2:name idd="VH">Victor Hugo</user2:name>
<nationality xmlns:user3="mynamespace3">French</nationality>
</author>
<t xmlns:user2="mynamespace2"/>
</authors>
the namespace "mynamespace2"
will be produced twice in the output.
The following transformation fixes this issue:
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:ext="http://exslt.org/common"
exclude-result-prefixes="ext">
<xsl:output method="text"/>
<xsl:key name="kNSbyURI" match="n" use="."/>
<xsl:template match="/">
<xsl:variable name="vrtfNS">
<xsl:for-each select=
"//namespace::*[not(. = ../../namespace::*)]">
<n><xsl:value-of select="."/></n>
</xsl:for-each>
</xsl:variable>
<xsl:variable name="vNS" select="ext:node-set($vrtfNS)/*"/>
<xsl:for-each select=
"$vNS[generate-id()
=
generate-id(key('kNSbyURI',.)[1])
]">
<xsl:value-of select="concat(., '
')"/>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
when this transformation is applied on the above XML document, it produces only all unique namespaces in the document:
http://www.w3.org/XML/1998/namespace
mynamespace
mynamespace2
mynamespace3
Part II: An XSLT 2.0 solution.
The XSLT 2.0 solution is a simple XPath 2.0 one-liner:
distinct-values(//namespace::*)
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