nodes from latest date attribute 1

[stinkybee]

Is there a way to get a node set from an xml file based on a date attribute. For example, I would like to get the child nodes of an element with a date attribute that has the latest date in it.

example xml

<data>
  <element date="01/01/06">
      ...child nodes of element
  </element>
  <element date="02/01/06">
      ...child nodes of element
  </element>
</data>

so using this exmaple I would like to retrieve the child elements of the element with a date attribute of "02/01/06", which is the latest date. I have been looking at XPath which looks like it might do the job but haven't found a specific solution to this problem.

 

[k5tm]

Do you have any control over the format of the date attribute value? if so, you could use xsl:sort on that attribute. (But you didn't mention what technology you are using to manipulate your XML document...)

Tom Morrison

http://www.liant.com

 

[stinkybee]

I am using asp, the date format doesn't matter to me really. I'm just using that as a possible example, I would be just as happy with an answer using a number instead of the date.

for example, getting the child nodes of the "element" with the highest id.

<data>
<element id="1">
...child nodes of element
</element>
<element id="2">
...child nodes of element
</element>
</data>

 

[k5tm]

This will work for a moderate size document. For a larger document, you should use a recursive solution. First, a slightly more interesting document:

<data>
  <element id="4">
      <someNode>This came from 4</someNode>
  </element>
  <element id="1">
      <someNode>This came from 1</someNode>
  </element>
  <element id="3">
      <someNode>This came from 3</someNode>
  </element>
  <element id="5">
      <someNode>This came from 5</someNode>
  </element>
  <element id="2">
      <someNode>This came from 2</someNode>
  </element>
</data>

Using this stylesheet:

<xsl:stylesheet version="1.0" xmlns:xsl="[URL unfurl="true"]http://www.w3.org/1999/XSL/Transform">[/URL]
<xsl:template match="/">
	<valueFound><xsl:value-of 
	             select="/data/element[not(../element/@id &gt; @id)]/someNode" />
	</valueFound>
</xsl:template>
</xsl:stylesheet>

This result produces:

<valueFound>This came from 5</valueFound>

Since you are using ASP (about which I know very little) I would guess that you would use the transformNode method.

Tom Morrison

http://www.liant.com

 

[k5tm]

Here is a recursive solution that will probably work better for larger documents:

<xsl:stylesheet version="1.0" xmlns:xsl="[URL unfurl="true"]http://www.w3.org/1999/XSL/Transform">[/URL]
<xsl:template match="/">
	<valueFound><xsl:apply-templates select="/data/element[1]" mode="find-maximum-id" />
	</valueFound>
</xsl:template>
<xsl:template match="element" mode="find-maximum-id">
   <xsl:variable name="next"
                 select="following-sibling::element[@id &gt; current()/@id]" />
   <xsl:choose>
      <xsl:when test="$next">
         <xsl:apply-templates select="$next" mode="find-maximum-id" />
      </xsl:when>
      <xsl:otherwise>
         <xsl:value-of select="someNode" />
      </xsl:otherwise>
   </xsl:choose>
</xsl:template>
</xsl:stylesheet>

Tom Morrison

http://www.liant.com

 

[stinkybee]

Thanks for these, they work a treat. Just in case anyone has a similar problem with ASP here is the code I used without using XSL.

set objLst = objXML.selectNodes("/data/element[not(../element/@id > @id)]/*")

This selects all child nodes of the "element" with the highest "id" attribute.

 

[stinkybee]

whilst we are on the subject, is there a way to extend this so that it selects the child nodes of an element based on the highest value of an attribute where there are two attributes.

example xml

<data>
  <element id="4" id2="">
      <someNode>This came from 4</someNode>
  </element>
  <element id="1" id2="">
      <someNode>This came from 1</someNode>
  </element>
  <element id="3" id2="6">
      <someNode>This came from 3</someNode>
  </element>
  <element id="5" id2="">
      <someNode>This came from 5</someNode>
  </element>
  <element id="2" id2="">
      <someNode>This came from 2</someNode>
  </element>
</data>

in this case I would like to pull out the values from the element with the highest "id" or the highest "id2", whichever is greater.