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Re: ancestor question
- To: xsl-list at lists dot mulberrytech dot com
- Subject: Re: [xsl] ancestor question
- From: Wendell Piez <wapiez at mulberrytech dot com>
- Date: Fri, 28 Sep 2001 18:55:08 -0400
- Reply-To: xsl-list at lists dot mulberrytech dot com
Amy,
If I construe this correctly, you are falling into a subtle trap that often
springs up to confound newer users.
The trick is, that the value of a node-set is the string value of the
*first* node in the node-set (in document order).
So when your context node is an Aps:Drawing, and you ask for <xsl:value-of
select="ancestor::Aps:VpmResultSet/Aps:PartStructure/Aps:Name"/>, the XPath
traverses all the way up to the ancestor VpmResultSet (actually all of
them, but you only have one), then down to collect all the Aps:Name
children of its Aps:PartStructure children. It then has a bunch of nodes
collected. But since you ask for the value, you get the value only of the
first one. That's why the Name that comes out is always the same ("assembly
1").
To identify correctly the Name that belongs to each Aps:Drawing, you need
to traverse in a way that will avoid this pitfall. It looks from your data
like going up just to ancestor::PartStructure (and no further), and then
down, would work.
As background, it may help you to know that the monster expression
ancestor::Aps:VpmResultSet/Aps:PartStructure/Aps:Name
is actually short for
ancestor::Aps:VpmResultSet/child::Aps:PartStructure/child::Aps:Name
(Seeing it explicit like this helps to dramatize how the steps work in the
location path. Given the XPath, you get back *all* the Aps:Name children of
*all* the Aps:PartStructure children of *all* the ancestor Aps:VpmResultSet
nodes of your context node. This may be many Names. When you ask for the
value, you get the value only of the first one.)
Does that help?
Regards,
Wendell
At 06:46 PM 9/27/01, you wrote:
>Here's my XML:
>
><?xml version="1.0"?>
><!DOCTYPE Aps:VpmResultSet SYSTEM
>"http://sofa.atc.lmco.com/assist/config/dtd/ApsVpmQueryResponse.dtd">
><Aps:VpmResultSet xmlns:Aps="http://www.assist.com/">
><Aps:PartStructure>
> <Aps:Name>assembly 1</Aps:Name>
> <Aps:PartNumber>1</Aps:PartNumber>
> <Aps:TopAssemblyName>pre assembly</Aps:TopAssemblyName>
> <Aps:AsDesigned>
> <Aps:Drawing>
> <Aps:Name>drawing assembly 1-1</Aps:Name>
> <Aps:DocumentId>314-1</Aps:DocumentId>
> <Aps:Sheets>
> <Aps:LocatorUrl>http://www.yahoo.com</Aps:LocatorUrl>
> </Aps:Sheets>
> </Aps:Drawing>
> <Aps:Drawing>
> <Aps:Name>drawing assembly 1-2</Aps:Name>
> <Aps:DocumentId>314-2</Aps:DocumentId>
> <Aps:Sheets>
> <Aps:LocatorUrl>http://www.yahoo.com</Aps:LocatorUrl>
> </Aps:Sheets>
> </Aps:Drawing>
> </Aps:AsDesigned>
></Aps:PartStructure>
><Aps:PartStructure>
> <Aps:Name>assembly 2</Aps:Name>
> <Aps:PartNumber>2</Aps:PartNumber>
> <Aps:TopAssemblyName>pre assembly</Aps:TopAssemblyName>
> <Aps:AsDesigned>
> <Aps:Drawing>
> <Aps:Name>drawing assembly 2</Aps:Name>
> <Aps:DocumentId>315</Aps:DocumentId>
> <Aps:Sheets>
> <Aps:LocatorUrl>http://www.yahoo.com</Aps:LocatorUrl>
> </Aps:Sheets>
> </Aps:Drawing>
> </Aps:AsDesigned>
></Aps:PartStructure>
></Aps:VpmResultSet>
>
>Here's my XSL:
>
><xsl:stylesheet version="1.0"
>xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
> xmlns:Aps="http://www.assist.com/"
> xmlns:xalan="http://xml.apache.org/xalan"
> exclude-result-prefixes="Aps">
> <xsl:output method="html" indent="yes"/>
> <xsl:param name="Name" select="."/>
>
> <xsl:template match="/">
> <xsl:for-each select="Aps:VpmResultSet/Aps:PartStructure">
> <xsl:for-each select="xalan:evaluate($Name)">
> <tr>
> <td><xsl:value-of
>select="ancestor::Aps:VpmResultSet/Aps:PartStructure/Aps:Name"/></td>
> <td><xsl:value-of
>select="ancestor::Aps:VpmResultSet/Aps:PartStructure/Aps:TopAssemblyName"/></td>
>
> <td><xsl:value-of
>select="ancestor::Aps:VpmResultSet/Aps:PartStructure/Aps:PartNumber"/></td>
>
> <td><xsl:value-of select="Aps:DocumentId"/></td>
> <td><a><xsl:attribute name="href">
> <xsl:value-of select="Aps:Sheets/Aps:LocatorUrl"/>
> </xsl:attribute><xsl:value-of select="Aps:Name"/>
> </a>
> </td>
> </tr>
> </xsl:for-each>
> </xsl:for-each>
> </xsl:template>
></xsl:stylesheet>
>
>I'm getting (I've ignored the href part for now):
><tr>
><td>assembly 1</td> <td>pre assembly</td> <td>1</td>
><td>314-1</td> <td>drawing assembly 1-1</td></tr>
><tr>
><td>assembly 1</td> <td>pre assembly</td> <td>1</td>
><td>314-2</td> <td>drawing assembly 1-2</td> </tr>
><tr>
><td>assembly 1</td> <td>pre assembly</td> <td>1</td>
><td>315</td> <td>drawing assembly 2</td></tr>
>
>but what I want is:
><tr>
><td>assembly 1</td> <td>pre assembly</td> <td>1</td>
><td>314</td> <td>drawing assembly 1</td></tr>
><tr>
><td>assembly 1</td> <td>pre assembly</td> <td>1</td>
><td>314-2</td> <td>drawing assembly 1-2</td> </tr>
><tr>
><td>assembly 2</td> <td>pre assembly</td> <td>2</td>
><td>315</td> <td>drawing assembly 2</td></tr>
>
>The xalan:evaluate() is sent in from a setParameter("Name", param) and
>seems to be working correctly.
>In this case param would be Aps:AsDesigned/Aps:Drawing, however I've
>just shown a section of the
>true XML. This param could be at different levels although the children
>will look the same.
>
>The xalan:evaluate section seems to work, it's just that I also need the
>ancestor information in the
>table and that doesn't seem to be doing what I thought it would.
>
>Could someone please tell me why this doesn't work and how I should go
>about fixing it?
======================================================================
Wendell Piez mailto:wapiez@mulberrytech.com
Mulberry Technologies, Inc. http://www.mulberrytech.com
17 West Jefferson Street Direct Phone: 301/315-9635
Suite 207 Phone: 301/315-9631
Rockville, MD 20850 Fax: 301/315-8285
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