GETTING COUNT AND POSITION using XSLT

udaybob · August 16th, 2009, 03:32 PM

Hi Guys,

Here is my requirement.

sample XML

<root>
<item>
...
<data name="x">...</data>
<data name="title">uday</data>
<data name="y">...</data>
....
</item>
<item>
...
<data name="x">...</data>
<data name="title">uday</data>
<data name="y">...</data>
....
</item>
<item>
...
<data name="x">...</data>
<data name="title">bhaskar</data>
<data name="y">...</data>
....
</item>
<item>
...
<data name="x">...</data>
<data name="title">bhaskar</data>
<data name="y">...</data>
....
</item>

<item>
...
<data name="x">...</data>
<data name="title">bhaskar</data>
<data name="y">...</data>
....
</item>

Desired o/p XML

<rss>
<item>
..
<position>1</position>
<total>2</total>
....
</item>
<item>
..
<position>2</position>
<total>2</total>
....
</item>
<item>
..
<position>1</position>
<total>3</total>
....
</item>
<item>
..
<position>2</position>
<total>3</total>
....
</item>
<item>
..
<position>3</position>
<total>3</total>
....
</item>
</rss>

for each item in the input xml, we get item in the output.
total represents the no. of items with the same title value
position represents the position of the item with a paticular title.

Iam using xslt 1.0

Thanks you in advance
Uday

mhkay · August 16th, 2009, 06:08 PM

First here is the XSLT 2.0 solution:

Code:

<xsl:for-each-group select="item" group-adjacent="data[@name='title']">
  <xsl:for-each select="current-group()">
     <item>
        <position><xsl:value-of select="position()"/></position>
        <count><xsl:value-of select="count(current-group())"/></count>
     </item>
  </xsl:for-each>
</xsl:for-each-group>

I hope this will persuade you that moving to XSLT 2.0 is a good idea if you possibly can.

I'm not going to attempt a 1.0 solution, it's too late in the evening, and frankly, coding this in 1.0 is not much fun. You basically need to have a recursive template that outputs one item and then calls itself to process the next, passing the current title and position as parameters. That part is fairly easy, the difficult bit is the count, where you need to "look ahead" in the recursion to see how many following items there are with the same key.

I'm assuming in both solutions that items with the same key are always adjacent in the input sequence.

udaybob · August 17th, 2009, 02:14 PM

Thank you very much. I tried your solution.Its working while seeing the output in the XML SPY since iam keeping the version as 2.0

i.e <xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

since we are using xalan i should be doing the same thing in xslt 1.0.

mhkay · August 17th, 2009, 02:27 PM

>since we are using xalan i should be doing the same thing in xslt 1.0.

Shouldn't that be:

"Since this requires XSLT 2.0 we should not be using Xalan"?

udaybob · August 17th, 2009, 03:53 PM

I don't know the exact reason,but soo far we developed all the xslt's in 1.0

When i tried to run the 2.0 version xslt, i got the below problem.

SystemId Unknown; Line #63; Column #44; Could not find function: current-group
SystemId Unknown; Line #63; Column #44; function token not found.
(Location of error unknown)java.lang.NullPointerException

So i came to conclusion that my java api which is responsible for transforming to XML is expecting 1.0 version.

Thanks
Uday

udaybob · August 17th, 2009, 04:25 PM

I mean to say the the java API build to transform the xml is based on XALAN. And it doesn't recognize the xslt 2.0 functions. Sorry if iam not giving the proper explanation.

Thanks
Uday

mhkay · August 17th, 2009, 05:13 PM

Yes, it looks as if you are running an XSLT 1.0 processor, probably Xalan. You need to run with a 2.0 processor, which in effect means Saxon.

udaybob · August 17th, 2009, 09:54 PM

Can you please help me out in writing the same code in 1.0 version? because i can not upgrade to 2.0 rightnow in my production environment.

mhkay · August 18th, 2009, 03:42 AM

No, sorry. I find writing XSLT 1.0 code really boring.

udaybob · August 18th, 2009, 07:57 AM

Its ok..no problem. Thank you for prompt replies.

Thanks a lot
Uday