====== XML / XSL notes ======

  * [[http://www.kohsuke.org/xmlschema/XMLSchemaDOsAndDONTs.html|W3C XML Schema: DOs and DON'Ts]] after Kohsuke Kawaguchi.
  * [[http://xpath.me/|Nice service]] to show visually matched XML nodes.
  * [[http://www.xmlplease.com/whitespace|Tricky whitespace handling in XSLT]] shows how to deal with space characters, carriage returns, line feeds or tabs.


=== [[stackoverflowa>2155970/267197|How to exclude given node from output XML tree?]] ===

<note question>
Suppose we have an XML tree from which we need to exclude the node ''<ns:to-exclude>''. That means the resulting tree should have all siblings and children of this node, but not the node itself.
</note>
<note tip>
<code xml>
<xsl:apply-templates select="ns:to-exclude/node()|*[not(self::ns:to-exclude)]" />
</code>
</note>


=== Why XML attributes declared as separate ''<xsd:element>'' entry should be used with explicit namespace prefix in XML? ===

<note question>
<code xml|XSD sample>
<xsd:schema xmlns="http://foo/bar" targetNamespace="http://foo/bar" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
	<xsd:attribute name="id" type="xsd:positiveInteger" />
 
	<xsd:element name="customer">
		<xsd:complexType>
			<xsd:attribute ref="id" use="required" />
		</xsd:complexType>
	</xsd:element>
</xsd:schema>
</code>

This XML does not validate:

<code xml|Failing XML>
<customer id="1" xmlns="http://foo/bar" />
</code>

Following XML samples validate fine:

<code xml|Correct XML>
<customer foo:id="1" xmlns="http://foo/bar" xmlns:foo="http://foo/bar" />
</code>
<code xml|Another correct XML>
<foo:customer foo:id="1" xmlns:foo="http://foo/bar" />
</code>
</note>
<note tip>
[[stackoverflowa>27644400/267197|Because such XML attributes form separate (independent) namespace group "Global Attribute Partition"]], thus they don't match element namespace even if they are literally the same.
Solution: either copy attribute declaration to each reference or use ''<xsd:elementGroup>'':

<code xml>
<xsd:schema xmlns="http://foo/bar" targetNamespace="http://foo/bar" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
	<xsd:attribute name="id" type="xsd:positiveInteger" />
 
	<xsd:element name="customer">
		<xsd:complexType>
			<xsd:attributeGroup ref="id" />
		</xsd:complexType>
	</xsd:element>

	<xsd:attributeGroup name="id">
		<xsd:attribute name="id" use="required" />
	</xsd:attributeGroup>
</xsd:schema>
</code>
</note>


=== How to implement stylesheet that will generate another stylesheet? ===

<note tip>
The given XSL will generate another XSL as output.
<note>All output XML elements need to be generated using ''<xsl:element>'' otherwise they cannot be separated from instructions of current XSL.</note>
<note>In order to generate extra namespaces, which are not explicitly used in resulting XML, we need to use a workaround described in [[stackoverflowa>12182435/267197|Create xmlns attribute in the XML using XSLT Transformation]], namely create a dummy node set and use extension to copy it's namespaces to current node.</note>
<note>It's handy to extra common logic into separate XSL and import it.</note>
<code xml>
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns="http://www.w3.org/1999/XSL/Transform" xmlns:extra="http://www.extra.org/exchange" version="1.0">

	<xsl:template match="text()|@*" />

	<xsl:variable name="dummy-node-set">
		<xsl:element name="extra:x" namespace="http://www.extra.org/exchange" />
	</xsl:variable>

	<xsl:template match="/">
		<xsl:element name="stylesheet">
			<xsl:attribute name="version">1.0</xsl:attribute>
			<xsl:copy-of select="ext:node-set($dummy-node-set)/*/namespace::*" />

			<!-- Some common/shared logic -->
			<xsl:element name="import">
				<xsl:attribute name="href">common.xsl</xsl:attribute>
			</xsl:element>

			<xsl:apply-templates />
		</xsl:element>
	</xsl:template>

	<xsl:template match="//extra:document/extra:number">
		<xsl:element name="template">
			<xsl:attribute name="match">//extra:document[<xsl:value-of select="../@index" />]/extra:number[text()='<xsl:value-of select="text()" />']</xsl:attribute>
			
			<xsl:element name="value-of">
				<xsl:attribute name="select">text()</xsl:attribute>
			</xsl:element>
		</xsl:element>
	</xsl:template>
</xsl:stylesheet>
</code>
</note>