Question

I have a for-each I want to sort by some value. But the thing I loop over only has a key that allows a connection to the value. A simple example for a document:

<foo>
  <keys>
    <key id="foo"/>
    <key id="bar"/>
  </keys>

  <things>
    <thing name="foo"><desc>some description</desc></thing>
    <thing name="bar"><desc>another description</desc></thing>
  </things>
</foo>

And a style sheet:

<xsl:for-each select="/foo/keys/key">
  <xsl:sort select="/foo/things/thing[@name=@id]"/>
  <xsl:value-of select="@id"/>
</xsl:for-each>

This doesn’t seem to work. @id relates to the key element from the loop; @name relates to thing from the predicate. How do I solve this? I tried assigning /foo/keys/key/@id to a variable and use that but <sort> must be the first element in a for-each…

Answer 1

Use current() function:

<xsl:sort select="/foo/things/thing[@name = current()/@id]"/>

Reference: http://www.w3.org/TR/xslt#misc-func

XML:

<foo>
    <keys>
        <key id="1"/>
        <key id="2"/>
        <key id="3"/>
        <key id="4"/>
    </keys>

    <things>
        <thing name="2">
            <desc>a</desc>
        </thing>
        <thing name="4">
            <desc>b</desc>
        </thing>
        <thing name="3">
            <desc>c</desc>
        </thing>
        <thing name="1">
            <desc>d</desc>
        </thing>
    </things>
</foo>

XSLT:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="text" />


    <xsl:template match="/">
        <xsl:for-each select="/foo/keys/key">
            <xsl:sort select="/foo/things/thing[@name = current()/@id]"/>
            <xsl:value-of select="@id"/>
        </xsl:for-each>
    </xsl:template>

</xsl:stylesheet>

Output:

2431