A Challenge...

AForgue · #1 (**permalink**) November 4th, 2003, 01:55 PM

How do you transform this:

Code:

<root>
   <folder label="Educational tools" level="1">Educational tools</folder>
   <folder label="Online Books" level="2">Online Books</folder>
   <folder label="Ebooks" level="3">Online Books</folder>
   <folder label="Reference Sites" level="2">Reference Sites</folder>
   <folder label="Textbooks" level="1">Textbooks</folder>
   <folder label="Trochim" level="2" >Trochim</folder>
</root>

To this:

Code:

<node label="Educational tools">
   <node label="Online Books">
      <node label="Ebooks"></node>
   </node>
   <node label="Reference Sites"></node>
</node>
<node label="Textbooks">
   <node label="Trochim"></node>
</node>

Note that the Level is what determines the depth of a node, it is assumed that the original XML is in order, so a Level 2 node appearing after a Level 1 node is assumed to be a child of it. Let me know if more clarification is needed.

-Aaron

armmarti · #2 (**permalink**) November 5th, 2003, 03:50 AM

Code:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>

    <xsl:template match="/">
        <root>
            <xsl:apply-templates select="/root/folder[@level=1]"/>
        </root>    
    </xsl:template>

    <xsl:template match="folder">
        <xsl:variable name="l" select="@level"/>
        <xsl:variable name="all-children" select="current()/following-sibling::*[@level = $l + 1][count(preceding-sibling::*[@level = $l][1] | current()) = 1]"/>
        <node>
            <xsl:copy-of select="@label"/>
            <xsl:apply-templates select="$all-children"/>
        </node>
    </xsl:template>
</xsl:stylesheet>

Regards,
Armen

shbyland · #3 (**permalink**) November 5th, 2003, 02:57 PM

Although Armen's solution definitely works, I just wanted to point out that if you come across these kinds of "unflattening" problems in the future, you might want to look into grouping techniques (see http://www.jenitennison.com/xslt/grouping or look under "Grouping" in the XSLT Programmer's Reference).

FYI -- a solution to a very similar problem was provided by Mr. Kay in the July 2002 archives under "Unflatten XML using XSLT". By slightly modifying his solution you can use:

<xsl:template match="root">
  <xsl:apply-templates select="folder[@level=1]"/>
</xsl:template>

<xsl:template match="folder">

  <node>
    <xsl:copy-of select="@label"/>
    <xsl:apply-templates select="following-sibling::*[@level=current()/@level+1][generate-id(current()) = generate-id(preceding-sibling::*[@level=current()/@level][1])]"/>
  </node>

</xsl:template>

and his explanation: "What this means is: process the following siblings of this element that have an @level that is one greater than the @level of this element, provided that the most recent preceding sibling of that element at the same level as the current element is the current element.

...sam

AForgue · #4 (**permalink**) November 5th, 2003, 04:14 PM

Amazing! My boss and I had been trying to figure this one out for a day and a half. This is somewhat close to what we were trying, but much more elegant and efficient. Thank you both (armmarti and shbyland) for lending your expertise.

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