How to use XSLT to create distinct values - xslt

Question

I have XML like this:
<items>
<item>
<products>
<product>laptop</product>
<product>charger</product>
</products>
</item>
<item>
<products>
<product>laptop</product>
<product>headphones</product>
</products>
</item>
</items>
I want it to output like
laptop
charger
headphones
I was trying to use distinct-values() but I guess i m doing something wrong. Can anyone tell me how to achieve this using distinct-values()? Thanks.
<xsl:template match="/">
<xsl:for-each select="//products/product/text()">
<li>
<xsl:value-of select="distinct-values(.)"/>
</li>
</xsl:for-each>
</xsl:template>
but its giving me output like this:
<li>laptop</li>
<li>charger</li>
<li>laptop></li>
<li>headphones</li>

Answer 1

An XSLT 1.0 solution that uses key and the generate-id() function to get distinct values:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet
version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" encoding="UTF-8" indent="yes"/>
<xsl:key name="product" match="/items/item/products/product/text()" use="." />
<xsl:template match="/">
<xsl:for-each select="/items/item/products/product/text()[generate-id()
= generate-id(key('product',.)[1])]">
<li>
<xsl:value-of select="."/>
</li>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>

Answer 2

Here's an XSLT 1.0 solution that I've used in the past, I think it's more succinct (and readable) than using the generate-id() function.
<xsl:template match="/">
<ul>
<xsl:for-each select="//products/product[not(.=preceding::*)]">
<li>
<xsl:value-of select="."/>
</li>
</xsl:for-each>
</ul>
</xsl:template>
Returns:
<ul xmlns="http://www.w3.org/1999/xhtml">
<li>laptop</li>
<li>charger</li>
<li>headphones</li>
</ul>

Answer 3

You don't want "output (distinct-values)", but rather "for-each (distinct-values)":
<xsl:template match="/">
<xsl:for-each select="distinct-values(/items/item/products/product/text())">
<li>
<xsl:value-of select="."/>
</li>
</xsl:for-each>
</xsl:template>

Answer 4

I came to this problem while working with a Sitecore XSL rendering. Both the approach that used key() and the approach that used the preceding axis performed very slowly. I ended up using a method similar to key() but that did not require using key(). It performs very quickly.
<xsl:variable name="prods" select="items/item/products/product" />
<xsl:for-each select="$prods">
<xsl:if test="generate-id() = generate-id($prods[. = current()][1])">
<xsl:value-of select="." />
<br />
</xsl:if>
</xsl:for-each>

Answer 5

distinct-values(//product/text())

Answer 6

I found that you can do what you want with XSLT 1.0 without generate-id() and key() functions.
Here is Microsoft-specific solution (.NET's XslCompiledTransform class, or MSXSLT.exe or Microsoft platfocm COM-objects).
It is based on this answer. You can copy sorted node set to variable ($sorted-products in the stylesheet below), then convert it to node-set using ms:node-set function. Then you able for-each second time upon sorted node-set:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0" xmlns:ms="urn:schemas-microsoft-com:xslt" exclude-result-prefixes="ms">
<xsl:output method="html" indent="yes" />
<xsl:template match="/">
<xsl:variable name="sorted-products">
<xsl:for-each select="//products/product">
<xsl:sort select="text()" />
<xsl:copy-of select=".|#*" />
</xsl:for-each>
</xsl:variable>
<xsl:variable name="products" select="ms:node-set($sorted-products)/product" />
<xsl:for-each select="$products">
<xsl:variable name='previous-position' select="position()-1" />
<xsl:if test="normalize-space($products[$previous-position]) != normalize-space(./text())">
<li>
<xsl:value-of select="./text()" />
</li>
</xsl:if>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
output:
<li>charger</li>
<li>headphones</li>
<li>laptop</li>
You can try it out in online playground.