XSLT: a variation on the pagination problem
- by MarcoS
I must transform some XML data into a paginated list of fields. Here is an example.
Input XML:
<?xml version="1.0" encoding="UTF-8"?>
<data>
<books>
<book title="t0"/>
<book title="t1"/>
<book title="t2"/>
<book title="t3"/>
<book title="t4"/>
</books>
<library name="my library"/>
</data>
Desired output:
<?xml version="1.0" encoding="UTF-8"?>
<pages>
<page number="1">
<field name="library_name" value="my library"/>
<field name="book_1" value="t0"/>
<field name="book_2" value="t1"/>
</page>
<page number="2">
<field name="book_1" value="t2"/>
<field name="book_2" value="t3"/>
</page>
<page number="3">
<field name="book_1" value="t4"/>
</page>
</pages>
In the above example I assume that I want at most 2 fields named book_n (with n ranging between 1 and 2) per page. Tags <page> must have an attribute number. Finally, the field named library_name must appear only the first <page>.
Here is my current solution using XSLT:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="2.0"
exclude-result-prefixes="trx xs">
<xsl:output method="xml" indent="yes" omit-xml-declaration="no" />
<xsl:variable name="max" select="2"/>
<xsl:template match="//books">
<xsl:for-each-group select="book" group-ending-with="*[position() mod $max = 0]">
<xsl:variable name="pageNum" select="position()"/>
<page number="{$pageNum}">
<xsl:for-each select="current-group()">
<xsl:variable name="idx" select="if (position() mod $max = 0) then $max else position() mod $max"/>
<field value="{@title}">
<xsl:attribute name="name">book_<xsl:value-of select="$idx"/>
</xsl:attribute>
</field>
</xsl:for-each>
<xsl:if test="$pageNum = 1">
<xsl:call-template name="templateFor_library"/>
</xsl:if>
</page>
</xsl:for-each-group>
</xsl:template>
<xsl:template name="templateFor_library">
<xsl:for-each select="//library">
<field name="library_name" value="{@name}" />
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
Is there a better/simpler way to perform this transformation?
