Re: [xsl] Correlation between two xml trees

[Joerg Heinicke <joerg dot heinicke at gmx dot de>]

Hello John,

it's not so difficult:

$data stores the z:row, you are currently processing. So with $data you can 
easily access this z:row. With the for-each you switch the context away from 
the z:row to $outputdef. The columns in $outputdef have an attribute 
@dbcolumn, which is normally accessed via <xsl:value-of select="@dbcolumn"/>.

Now from the z:row in $data you want to get the value of either @col1, @col2 
or @col3. The attribute you want to access is stored in @dbcolumn. So you 
want to have the value of this attribute, whose name is the same as the 
value stored in @dbcolumn.

$data/@* means "all attributes of the z:row stored in $data".

The predicate [] restricts the selection of this expression. Everything in 
the predicate refers to the node/attribute/etc. directly before the 
predicate. So @*[name()] means the name() of the attribute.

With current() we switch the context away from these attributes to the 
context element, which is at the moment a column from $outputdef/root/cloumn 
(see for-each).

So

$data/@*[name()=current()/@dbcolumn]

means

return the value of all the attributes, whose name() is the same as the 
value of the @dbcolumn of the currently processed element. Of course this is 
only one. (<xsl:value-of/> also selects always only the value of the first 
node/attribute in a nodeset.)

I hope, this explanation was not to much,to less or to buggy ;-)

Regards,

Joerg


John Sands wrote:

> Hi Joerg,
>
> Thank you very much. It works, but I'd like to understand it.
>
>
> > <xsl:template match="z:row">
> >   <data>
> >     <xsl:variable name="data" select="."/>
> >     <xsl:for-each select="$outputdef/root/column">
> >       <xsl:element name="{@tagname}">
> >         <xsl:value-of select="$data/@*[name()=current()/@dbcolumn]"/>
> >       </xsl:element>
> >     </xsl:for-each>
> >   </data>
> > </xsl:template>
>
> I understand the use of the xsl:variable, but the rest of the expression
> is still baffling to me:
>
>     select="$data/@*[name()=current()/@dbcolumn]"
>
> Can you explain what it does, please?
>
> Thanks,
> John Sands

--

System Development
VIRBUS AG
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Fax  +49(0)341-979-7409
joerg.heinicke@virbus.de
www.virbus.de


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