Sorting XML elements

nagesh has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks,

I have example XML file below. Some elements in XML have location. I want to sort the XML elements according to the "location" child element of each elements. In the same time I don't want to loose the XML tree structure i.e the parents and children after sort have to remain the same. I want to use the "X" attributes of the location for sorting. If "X" attributes are same then "Y" attribute gets the priority. The sort have to be ascending order. I was thinking of using the XML::DOM module for this, but I am confused as to how I should rebuild the XML according to the sort. I appreciate suggestions about to how to go about and any modules that could be of help to me.

thanks,

Nagesh

<?xml version="1.0" encoding="UTF-8"?>

<VB.Form name="RFI002">
     <VB.Frame name="framain">
          <Font>
               <Name>Tahoma</Name>
               <Size>8.25</Size>
               <Charset>0</Charset>
               <Weight>400</Weight>
               <Underline>0   'False</Underline>
               <Italic>0   'False</Italic>
               <Strikethrough>0   'False</Strikethrough>
          </Font>
          <location X="0" Y="-120" />
          <size H="4635" W="10455" />
          <VB.Frame name="Frasch">
               <BorderStyle>0  'None</BorderStyle>
               <location X="1920" Y="1800" />
               <size H="495" W="2175" />
               <formfield name="optschyes">
                    <type object="VB.OptionButton" />
                    <Font>
                         <Name>Tahoma</Name>
                         <Size>8.25</Size>
                         <Charset>0</Charset>
                         <Weight>400</Weight>
                         <Underline>0   'False</Underline>
                         <Italic>0   'False</Italic>
                         <Strikethrough>0   'False</Strikethrough>
                    </Font>
                    <location X="0" Y="120" />
                    <size H="255" W="855" />
               </formfield>
               <formfield name="optschno">
                    <type object="VB.OptionButton" />
                    <Font>
                         <Name>Tahoma</Name>
                         <Size>8.25</Size>
                         <Charset>0</Charset>
                         <Weight>400</Weight>
                         <Underline>0   'False</Underline>
                         <Italic>0   'False</Italic>
                         <Strikethrough>0   'False</Strikethrough>
                    </Font>
                    <location X="840" Y="120" />
                    <size H="255" W="1095" />
               </formfield>
          </VB.Frame>
          <VB.Frame name="Fracost">
               <BorderStyle>0  'None</BorderStyle>
               <location X="1920" Y="2280" />
               <size H="495" W="1935" />
               <formfield name="optno">
                    <type object="VB.OptionButton" />
                    <Font>
                         <Name>Tahoma</Name>
                         <Size>8.25</Size>
                         <Charset>0</Charset>
                         <Weight>400</Weight>
                         <Underline>0   'False</Underline>
                         <Italic>0   'False</Italic>
                         <Strikethrough>0   'False</Strikethrough>
                    </Font>
                    <location X="840" Y="120" />
                    <size H="255" W="1095" />
               </formfield>
               <formfield name="optyes">
                    <type object="VB.OptionButton" />
                    <Font>
                         <Name>Tahoma</Name>
                         <Size>8.25</Size>
                         <Charset>0</Charset>
                         <Weight>400</Weight>
                         <Underline>0   'False</Underline>
                         <Italic>0   'False</Italic>
                         <Strikethrough>0   'False</Strikethrough>
                    </Font>
                    <location X="0" Y="120" />
                    <size H="255" W="855" />
               </formfield>
          </VB.Frame>
          <formfield name="Cmbreason">
               <type object="VB.ComboBox" />
               <location X="1920" Y="840" />
               <size H="315" W="2175" />
          </formfield>
          <formfield name="txtbehalf">
               <type object="VB.TextBox" />
               <Font>
                    <Name>Tahoma</Name>
                    <Size>8.25</Size>
                    <Charset>0</Charset>
                    <Weight>400</Weight>
                    <Underline>0   'False</Underline>
                    <Italic>0   'False</Italic>
                    <Strikethrough>0   'False</Strikethrough>
               </Font>
               <Text>[Mr. Jim Mcdongaller (Org/Org Unit)]</Text>
               <location X="1920" Y="360" />
               <size H="285" W="3985" />
          </formfield>
     </VB.Frame>
</VB.Form>
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Re: Sorting XML elements by IOrdy (Friar) on Feb 20, 2002 at 01:42 UTC
If you are sorting for display you dont need to sort and rebuild the XML tree at all. Just iterate over the node parent according to the X then Y attributes of the <location> child. If you really want to sort your file and save, then I think the simplest way would be to build a new tree and add in nodes as they are sorted. Then save your new xml tree over the top of the old. I find Xpath easier to bend my mind around so I have been using XML::LibXML which gives you the option of mixing and matching between XPath and DOM according to the task.	[reply]
Re: Sorting XML elements by gellyfish (Monsignor) on Feb 20, 2002 at 12:38 UTC
You might consider using XSLT to do the sorting using (unsurprisingly) 'xsl:sort' - unfortunately XML::XSLT doesn't support this yet but XML::LibXSLT does. /J\	[reply]