Question

Given the following XML:

<root>
  <StepFusionSet name="SF1">
      <StepFusionSet name="SF2">
      </StepFusionSet>
  </StepFusionSet>
  <StepFusionSet name="SF10">
  </StepFusionSet>
</root>

The following C# code :

        XPathDocument doc = new XPathDocument("input.xml");
        var nav = doc.CreateNavigator();

        var item = nav.Select("//StepFusionSet[@name]");
        while (item.MoveNext())
        {
            Debug.WriteLine(item.Current.GetAttribute("name", item.Current.NamespaceURI));
        }

Gives me the output :

SF1
SF2
SF10

But the following XSLT file :

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

  <xsl:template match="//StepFusionSet">
    <xsl:call-template name="a"/>
  </xsl:template>

  <xsl:template name="a">
      <xsl:apply-templates select="@name"/>
  </xsl:template>
</xsl:stylesheet>

(called by C# code:)

        XslTransform xslt = new XslTransform();
        xslt.Load("transform.xslt");
        XPathDocument doc = new XPathDocument("input.xml");
        MemoryStream ms = new MemoryStream();

        xslt.Transform(doc, null, ms);

Gives me the output :

SF1
SF10

What I’m doing wrong in my XSLT file?

Answer 1

Consider your first template…

<xsl:template match="//StepFusionSet">

…as applied to your SF1 and (nested) SF2 elements:

<StepFusionSet name="SF1">
  <StepFusionSet name="SF2">
  </StepFusionSet>
</StepFusionSet>

The template matches your outer SF1 element; however, it then needs to be reapplied to the children of the matched element in order to match your inner SF2.

This can be achieved by embedding a recursive <xsl:apply-templates/> inside your second template definition:

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

  <xsl:template match="//StepFusionSet">
    <xsl:call-template name="a"/>
  </xsl:template>

  <xsl:template name="a">
    <xsl:apply-templates select="@name"/>
    <xsl:apply-templates/>
  </xsl:template>

</xsl:stylesheet>

Alternatively, you can use an <xsl:for-each> element to select all your <StepFusionSet> elements (including nested ones such as SF2):

<?xml version="1.0" ?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
  <xsl:output method="xml" indent="yes"/>
  <xsl:template match="/">
    <xsl:for-each select="//StepFusionSet">
      <xsl:value-of select="@name"/>
    </xsl:for-each>
  </xsl:template>
</xsl:stylesheet>