Question

Here is sample xml

<Data version="2.0">
   <Group>
        <Item>3</Item>
        <Item>1</Item>
        <Item>2</Item>
   </Group>
   <Group>
        <Item>7</Item>
        <Item>5</Item>
   </Group>
</Data>

And for ordering nodes in Group by Item value I tried to use the following xsl:

  <xsl:template match="/Data">

    <xsl:apply-templates select="Group">
      <xsl:sort select="Item" />
    </xsl:apply-templates>

  </xsl:template>

But get only values, even without sorting:

    3
    1
    2

    7
    5

So the questions are: 1. why sorting not work 2. How to keep all nodes and keep structure of xml?

Answer 1

@Jim’s answer is basically correct.

However, applied to a slightly more realistic XML document, such as this:

<Data version="2.0">
   <Group>
        <Item>3</Item>
        <Item>1</Item>
        <Item>10</Item>
        <Item>2</Item>
   </Group>
   <Group>
        <Item>7</Item>
        <Item>5</Item>
   </Group>
</Data>

the result produced is clearly not what you want (10 comes before 2 and 3):

<?xml version="1.0" encoding="utf-8"?>
<Data version="2.0">

   <Group>
      <Item>1</Item>
      <Item>10</Item>
      <Item>2</Item>
      <Item>3</Item>
   </Group>

   <Group>
      <Item>5</Item>
      <Item>7</Item>
   </Group>

</Data>

Here is a correct solution (that is also slightly shorter):

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>

 <xsl:template match="node()|@*">
  <xsl:copy>
   <xsl:apply-templates select="node()|@*"/>
  </xsl:copy>
 </xsl:template>

 <xsl:template match="Group">
  <Group>
   <xsl:apply-templates select="*">
    <xsl:sort data-type="number"/>
   </xsl:apply-templates>
  </Group>
 </xsl:template>
</xsl:stylesheet>

when this transformation is applied on the same XML document (above), the wanted, correct result is produced:

<Data version="2.0">
   <Group>
      <Item>1</Item>
      <Item>2</Item>
      <Item>3</Item>
      <Item>10</Item>
   </Group>
   <Group>
      <Item>5</Item>
      <Item>7</Item>
   </Group>
</Data>

Explanation: Use of the data-type attribute of <xsl:sort> to specify that the sort keys value should be treated as number, not as (the default) string.