Re: [xslt] Issues using parameters with namespaces

[Nick Wellnhofer <wellnhofer aevum de>]

On 28/02/2022 22:07, George Joseph wrote:
> Actually "//*[name()='dm:device']" works as well so maybe that's what I'll do.

This seems like the best work-around.

>     Is there any reason why path parameters with namespaces haven't been
>     supported?
>     Would a pull request to add the namespaces in xsltNewTransformContext be
>     considered?

How parameters are passed isn't covered by the standard, so it's up to the 
implementation to come up with something. It seems natural to allow XPath 
expressions, but it's not clear how to handle namespaces. Simply taking the 
namespace defitinions from the root element of the root stylesheet should do 
what most people expect, but it is somewhat fragile.

1. Passing parameters from the command line

Supporting namespaces in a clean way would probably require a separate channel 
to register namespaces just for parameter evaluation. Even Saxon doesn't seem 
to support custom namespaces in parameter expressions:

"The static context for this XPath expression includes only the standard 
namespaces conventionally bound to the prefixes xs, fn, xsi, and saxon." [1]

2. Passing parameters using the API

The most flexible approach is probably an API to set parameters directly, 
similar to Saxon's XsltTransformer [2]. This would even allow to pass nodes 
from external documents as parameters. But if you want to combine that with 
XPath expressions, you'd have to evaluate them yourself.

Nick


[1] https://www.saxonica.com/documentation11/index.html#!using-xsl/commandline
[2] 
https://www.saxonica.com/documentation11/index.html#!javadoc/net.sf.saxon.s9api/XsltTransformer@setParameter