RE: [xsl] Merging Two Files and Removing Duplicate Nodes

["Michael Kay" <mhkay at iclway dot co dot uk>]

> I am trying to merge two files so that the output contains
> only products
> that have matching codes on both files.  In addition, I don't want the
> output to contain duplicate child elements under product
> I've been able to get matching products using the folllowing
> xsl and then
> copy the children from each file.  I just haven't figured how
> to exclude
> child nodes from the second file if they exist on the first file.
>
> <xsl:template match="/">
>     <xsl:apply-templates
> select="*//product[./code=document($second-file)//product/code]"/>
> </xsl:template>

Unless your processor is very clever, that's going to have O(m*n)
performance. I'd strongly recommend using keys, even though you can no
longer do the selection in one XPath statement:

<xsl:key name="prod2" match="second-file-list/product" use="code"/>

<xsl:template match="/">
  <xsl:for-each select="first-file-list/product">
    <xsl:variable name="code" select="code"/>
    <xsl:for-each select="document($second-file)">
      <xsl:apply-templates select="key('prod2', $code)">

This will process all the products on the second file that also exist on the
first file; products that are not present on both files will not be
processed.

Mike Kay
Software AG


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