Re: [xsl] IDREFS and key()

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

At 2005-11-28 18:30 -0800, Dan Vint wrote:
> I have an element that contains an IDREFS attribute like the following:
>
> <Attribute id="aAtt" references="foo bar"><Name>Att</Name></Attribute>
>
> The references attribute is defined as an IDREFS and the schema and 
> document that this lives in are all valid.
>
> I want to use the references attribute in a key definition so I can 
> reverse the relationship and in this case from the element 
> identified as foo or bar, indicate that the Attribute element, named 
> Att links to it.
>
> My key definition is this:
>
> <xsl:key name="attribute-references" match="Attribute" use="@references"/>

You've got this backwards ... but even straightening it out won't 
help you with ID/IDREFS.  You load key tables with the nodes being 
looked up, not with the nodes with the lookup values.

When mimicking ID/IDREF (not ID/IDREFS) you can load the key table 
with <xsl:key> matching the elements with the id= attribute using the 
value of the id= attribute, and then use the key() function with the 
IDREF attribute for the lookup.

But it doesn't work for ID/IDREFS, only for mimicking ID/IDREF.

> ...
> It seems like the key() is trying to match my value of 'foo' against 
> the complete string of 'foo bar', rather than doing a "contains" 
> sort of match.

Indeed it is, by definition.

> Is this what is expected?

Yes.

> When I provide the full 'foo bar' to the for-each I now match this 
> Attribute definition.

As it should.

> How do I get the key() function to break up the IDREFS

You can't in XSLT 1.0.

> and process the individual values? I tried using id() in the key 
> definition but that didn't help.

Right ...

But the id() function *would* work if you had the luxury of declaring 
the ID-typed attribute of the elements with the id= attributes:

  <!ATTLIST element-name-here id ID #IMPLIED>

This can go in the internal declaration subset of your document, or 
in an external declaration subset pointed to by the DOCTYPE SYSTEM 
identifier.  Note that you do *not* need the <!ELEMENT> declaration, 
just the <!ATTLIST> will do.  Then you don't even need keys and the 
id() function will work.  I often do this in a chain of transforms by 
having the output of one transform have the system identifier of a 
one-line DTD file that has only the ATTLIST declaration.

But not every has the luxury of injecting the attribute list 
declaration by any means.

I hope this helps.

. . . . . . . . . . Ken

--
Upcoming XSLT/XSL-FO hands-on courses:  Denver,CO March 13-17,2006
World-wide on-site corporate, govt. & user group XML/XSL training.
G. Ken Holman                 mailto:gkholman@xxxxxxxxxxxxxxxxxxxx
Crane Softwrights Ltd.          http://www.CraneSoftwrights.com/s/
Box 266, Kars, Ontario CANADA K0A-2E0    +1(613)489-0999 (F:-0995)
Male Cancer Awareness Aug'05  http://www.CraneSoftwrights.com/s/bc
Legal business disclaimers:  http://www.CraneSoftwrights.com/legal