Wrap some fields in CDATA but not others OF THE SAME NAME - xslt

Question

Forking from a previous question I asked, how do I ensure that example/one/field and example/three/field are enclosed in CDATA whilst example/two/field is not?
Input:
<?xml version="1.0"?>
<example>
<one>
<field>CDATA required here</field>
</one>
<two>
<field>No CDATA thanks</field>
</two>
<three>
<field>More CDATA please</field>
</three>
</example>
Required output:
<?xml version="1.0"?>
<example>
<one>
<field><![CDATA[CDATA required here]]></field>
</one>
<two>
<field>No CDATA thanks</field>
</two>
<three>
<field><![CDATA[More CDATA please]]></field>
</three>
</example>
I could specify <xsl:output cdata-section-elements="field"/> but this will affect example/two/field as well. I have tried putting in a path like <xsl:output cdata-section-elements="example/one/field example/three/field"/> but this produces an error (Error XTSE0280: Invalid element name. Invalid QName {example/one/field}). Where am I going wrong?

Answer 1

With your current markup I don't think there is a clean way with XSLT. You would need to use different element names or different namespaces at least to allow you and the XSLT processor's serializer to distinguish which elements to output as CDATA sections and which not.
Or you would need to consider to use disable-output-escaping e.g.
<xsl:template match="one/field | three/field">
<xsl:copy>
<xsl:text disable-output-escaping="yes"><![CDATA[<![CDATA[]]></xsl:text>
<xsl:value-of select="."/>
<xsl:text disable-output-escaping="yes">]]></xsl:text>
</xsl:copy>
</xsl:template>
[edit]
Here is a complete sample stylesheet:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="#* | node()">
<xsl:copy>
<xsl:apply-templates select="#* | node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="one/field | three/field">
<xsl:copy>
<xsl:text disable-output-escaping="yes"><![CDATA[<![CDATA[]]></xsl:text>
<xsl:value-of select="."/>
<xsl:text disable-output-escaping="yes">]]></xsl:text>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
Note however that disable-output-escaping is an optional serialization feature that is not supported by all XSLT processors.