The XSLT <xsl:value-of> element is used to extract a value from an expression defined in the select attribute.
The expression defined in the mandatory select attribute is either an XPATH expression (for nodes and/or values) or a variable reference.
The return of the <xsl:value-of> function is a literal value.
Syntax
<xsl:value-of select="expression" />
Attributes
| name | mandatory/optional | description |
| select | MANDATORY | an XPATH expression or variable reference. |
| disable-output-escaping | OPTIONAL | determines if escaped characters in the output are converted to normal characters |
Examples
For our examples we are using the fictional library as an input XML. Any XSL transform examples we define uses this XML as an input.
<?xml version="1.0" encoding="UTF-8"?>
<library>
<category name="dogs">
<book>
<name>All about dogs</name>
<author>Someone</author>
<isin>true</isin>
<daysuntilreturn>0</daysuntilreturn>
</book>
</category>
<category name="cats">
<book>
<name>All about cats</name>
<author>Someone</author>
<isin>false</isin>
<daysuntilreturn>3</daysuntilreturn>
</book>
</category>
</library>
How to select a node value
The following XSL transform shows how to retrieve an arbitrary node (element or attribute) value from a source document and write it to a target document.
This example matches each category node, and then uses the <xsl:value-of> function to retrieve and print the category name.
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<xsl:apply-templates select="/*/category"/>
</xsl:template>
<xsl:template match="category">
Found a category: <xsl:value-of select="./@name" />
</xsl:template>
</xsl:stylesheet>
The output from the above XSL transform is as follows:
Found a category: dogs
Found a category: cats
How to select an XPATH expression value
The following XSL transform shows how to use an XPATH expression to generate a value and then write the result as an output to a target document.
This example uses XPATH to count of each category node in the source document and print the result.
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
Number of categories: <xsl:value-of select="count(//category)" />
</xsl:template>
</xsl:stylesheet>
The output from the above XSL transform is as follows:
Number of categories: 2
How to select a variable value
The following XSL transform shows how to query a variable and write its value as an output to a target document.
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:variable name="my_constant" select="'a constant value'" />
<xsl:variable name="some_value" select="/*/category[@name='dogs']/book[1]/name" />
<xsl:template match="/">
Variable (Constant): <xsl:value-of select="$my_constant" />
Variable (Select): <xsl:value-of select="$some_value" />
</xsl:template>
</xsl:stylesheet>
The output from the above XSL transform is as follows:
Variable (Constant): a constant value
Variable (Select): all about dogs