Sorting XML file by attribute

Question

Hi, I have a following XML code:

<Group>
    <GElement code="x">
        <Group>
            <GElement code="x">
                <fname>a</fname>
                <lname>b</lname>
            </GElement>
            <GElement code ="f">
                <fname>fa</fname>
            </GElement>
        </Group>
    </GElement>
    <GElement code ="f">
    </GElement>
</Group>

I would like to have the output sorted by "code" like:

<Group>
    <GElement code ="f">
    </GElement>
    <GElement code="x">
        <Group>
            <GElement code ="f">
                <fname>fa</fname>
            </GElement>
            <GElement code="x">
                <fname>a</fname>
                <lname>b</lname>
            </GElement>
        </Group>
    </GElement>
</Group>

The depth of the tree can be endless i.e. the GElement can have another Group and so on.

Any ideas?

Answer 1

Use XslCompiledTransform (see MSDN) to apply this styleshet to your XML document:

<xsl:stylesheet
  version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>
  <!-- the identity template copies everything verbatim -->
  <xsl:template match="node()|@*">
    <xsl:copy>
      <xsl:apply-templates select="node()|@*" />
    </xsl:copy>
  </xsl:template>

  <!-- special template for <Group> that sorts its children -->
  <xsl:template match="Group">
    <xsl:copy>
      <xsl:copy-of select="@*" /> <!-- copy attributes, if any -->
      <xsl:apply-templates select="GElement">
        <xsl:sort select="@code" />
      </xsl:apply-templates>
    </xsl:copy>
  </xsl:template>
</xsl:stylesheet>

XML tree nesting depth can be arbitrary.