nilled()

Description

nilled() returns xs:boolean true if the argument is an element node that has been schema-validated and has its nilled property set — i.e., the element carries xsi:nil="true" and its schema type permits nilling.

For elements that have not been schema-validated, or for non-element nodes, the function returns false. If the argument is the empty sequence, the empty sequence is returned.

In practice, nilled() is used with schema-aware processors (such as Saxon-EE) to distinguish a genuinely absent value (xsi:nil="true") from an element that is simply empty.

Parameters

Return value

xs:boolean? — true if the element is nilled, false if it is not, or the empty sequence if the argument is the empty sequence.

Examples

Filter out nilled elements

Input XML (schema-validated):

<?xml version="1.0" encoding="UTF-8"?>
<employees xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <employee id="1"><name>Alice</name></employee>
  <employee id="2" xsi:nil="true"/>
  <employee id="3"><name>Charlie</name></employee>
</employees>

Stylesheet:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <xsl:output method="xml" indent="yes"/>

  <xsl:template match="/employees">
    <active-employees>
      <xsl:copy-of select="employee[not(nilled(.))]"/>
    </active-employees>
  </xsl:template>
</xsl:stylesheet>

Output:

<active-employees>
  <employee id="1"><name>Alice</name></employee>
  <employee id="3"><name>Charlie</name></employee>
</active-employees>

Report nil status of each element

Stylesheet:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" indent="yes"/>

  <xsl:template match="/employees">
    <report>
      <xsl:for-each select="employee">
        <entry id="{@id}" nilled="{nilled(.)}"/>
      </xsl:for-each>
    </report>
  </xsl:template>
</xsl:stylesheet>

Notes

• nilled() only returns true for schema-validated elements with xsi:nil="true" and a nillable type in the schema. Without schema validation, it always returns false.
• For non-schema-aware processing, checking @xsi:nil = 'true' directly is a common alternative.
• This function is defined in XPath 2.0 and is not available in XSLT 1.0.

See also

• node-name()
• base-uri()