Re: [xsl] Problem with "except" operator

["G. Ken Holman" <gkholman@xxxxxxxxxxxxxxxxxxxx>]

At 2009-02-11 14:44 +0100, Felix Nensa wrote:
> I have a weird problem where the "except" operator does not behave as
> I would expect it.

You are incorrectly treating "except" with node values, instead of as 
node identity.

> Given the following input source XML:
>
> <root>
>   <Response>
>     <Users>
>       <Count>2</Count>
>       <User>
>         <Username>henry</Username>
>         <Online>false</Online>
>         <UserId>302</UserId>
>       </User>
>       <User>
>         <Username>felix</Username>
>         <Online>false </Online>
>         <UserId>288</UserId>
>       </User>
>     </GetUserList>
>   </Response>
>   <Response>
>     <Friends>
>       <Count>1</Count>
>       <Friend>
>         <UserId>288</UserId>
>       </Friend>
>     </Friends>
>   </Response>
> </root>
>
> I am trying to get all those Users wich are not in the list of Friends
> with the following expression:
>
> <xsl:variable name="users" select="//Users/User/UserId" />
> <xsl:variable name="friends" select="//Friends/Friend/UserId" />
>
> <!-- debug output -->
> <xsl:value-of select="$users except $friends" />
>
> It outputs: 302 288
> I would expect: 302

The expression:

  $A except $B

... will give you those nodes in $A that are not also nodes in 
$B.  Not the values of the nodes, but the nodes themselves.

> I am using the latest version of Saxon.

Always a wise choice!

You want to deal with node value by using the "=" operator ... I have 
an example below.  Checking a scalar against the set returns false 
when the operator is false for all members of the set, or true when 
the operator is true for any member of the set.

I hope this helps.

. . . . . . . Ken

T:\ftemp>type felix.xml
<root>
  <Response>
    <Users>
      <Count>2</Count>
      <User>
        <Username>henry</Username>
        <Online>false</Online>
        <UserId>302</UserId>
      </User>
      <User>
        <Username>felix</Username>
        <Online>false </Online>
        <UserId>288</UserId>
      </User>
    </Users>
  </Response>
  <Response>
    <Friends>
      <Count>1</Count>
      <Friend>
        <UserId>288</UserId>
      </Friend>
    </Friends>
  </Response>
</root>

T:\ftemp>type felix.xsl
<?xml version="1.0" encoding="US-ASCII"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
                version="2.0">

<xsl:output method="text"/>

<xsl:template match="/">
<xsl:variable name="users" select="//Users/User/UserId" />
<xsl:variable name="friends" select="//Friends/Friend/UserId" />

<!-- debug output -->
<xsl:value-of select="$users [. != $friends]" />
</xsl:template>

</xsl:stylesheet>
T:\ftemp>xslt2 felix.xml felix.xsl
302
T:\ftemp>

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