Question

Ive got a long list of xml elements.

Each element got an ID and a PARENT_ID.

How can I make a sitemap/nested list based on this? The elements with null value is the top parent elements.

I want to show the list with UL and LI`s in HTML.

<ROOT>
<SITEMAP>
    <ARRAY>
        <ID>1</ID>
        <NAME>Test</NAME>
        <PARENT_ID>NULL</PARENT_ID>
    </ARRAY>
    <ARRAY>
        <ID>2</ID>
        <NAME>Test2</NAME>
        <PARENT_ID>3</PARENT_ID>
    </ARRAY>
    <ARRAY>
        <ID>3</ID>
        <NAME>Test3</NAME>
        <PARENT_ID>NULL</PARENT_ID>
    </ARRAY>
    <ARRAY>
        <ID>4</ID>
        <NAME>Test4</NAME>
        <PARENT_ID>1</PARENT_ID>
    </ARRAY>
    <ARRAY>
        <ID>5</ID>
        <NAME>Test5</NAME>
        <PARENT_ID>4</PARENT_ID>
    </ARRAY>
</SITEMAP>

Answer 1

The key template will look something like this:

<xsl:template matches="ARRAY"> 
   <xsl:variable name="id" select="ID"/>
   <output>
      <!-- output goes here -->
      ...
      <!-- now process every ARRAY with a PARENT_ID equal to the current node's id. (I.e. its children.) -->
      <xsl:apply-templates select="/ROOT/SITEMAP/ARRAY[PARENT_ID = $id]"/>
   </output>
</xsl:template>

And you kick it off with:

<xsl:template matches="/">
   <xsl:apply-templates select="/ROOT/SITEMAP/ARRAY[PARENT_ID = 'NULL']"/>
</xsl:template>

Be aware though that if there are any cycles in your hierarchy, this transformation will run infinitely.