Re: Issues using parameters with namespaces

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On Mon, Feb 28, 2022 at 11:42 AM Nick Wellnhofer <[email protected]>
wrote:

> On 28/02/2022 18:50, George Joseph via xslt wrote:
> > I've been having a heck of a time trying to pass a parameter
> > to xsltApplyStylesheet
> > that has namespaces in the xpath expression.
>
> This use case is simply not supported.
>

Okaaaaay.


>
> > Finally I did find a workaround by calling xsltNewTransformContext()
> then
> > iterating
> > over the nsDefs in the stylesheet document and
> calling xmlXPathRegisterNs on
> > ctxt->xpathCtxt for each nsDef.
>
> I'm a bit puzzled that this worked at all. See the code here:
>
>
>
> https://gitlab.gnome.org/GNOME/libxslt/-/blob/master/libxslt/variables.c#L1581


 I think it works because xsltProcessUserParamInternal only sets
xpctxt->namespaces = NULL but it doesn't clear xpctxt->nsHash which is where
xmlXPathRegisterNs puts the namespaces to be registered.

>
>
> But the expression is compiled before resetting the namespaces, so I guess
> that's why.
>
> > I would have thought this would have been done automatically though.
> Did I
> > miss something or is there a better way to do this?
>
> No, I'd recommend that you only use string and integer params.
>

Can you give me a hint?   I've had absolutely no luck is trying to pass a
path
as a string and getting it to result in something other than "The 'select'
expression
did not evaluate to a node set" even in an absurdly simple example.  I'm
passing
the path double quoted "'/dm:device'" and have tried various combinations of
"select=" and "with-param".    Even Google is failing me so any help would
be appreciated.

Thanks!



>
> Nick
>

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<div dir=3D"ltr"><div dir=3D"ltr"><br></div><div class=3D"gmail_quote"><div=
 dir=3D"ltr" class=3D"gmail_attr">On Mon, Feb 28, 2022 at 11:42 AM Nick Wel=
lnhofer &lt;<a href=3D"mailto:[email protected]" target=3D"_blank">wellnh=
[email protected]</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" sty=
le=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);paddi=
ng-left:1ex">On 28/02/2022 18:50, George Joseph via xslt wrote:<br>
&gt; I&#39;ve been having a heck of a time trying to pass a parameter <br>
&gt; to=C2=A0xsltApplyStylesheet<br>
&gt; that has namespaces in the xpath expression.<br>
<br>
This use case is simply not supported.<br></blockquote><div><br></div><div>=
Okaaaaay.</div><div>=C2=A0</div><blockquote class=3D"gmail_quote" style=3D"=
margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-lef=
t:1ex">
<br>
&gt; Finally I did find a workaround by calling=C2=A0xsltNewTransformContex=
t() then <br>
&gt; iterating<br>
&gt; over the nsDefs in the stylesheet document and calling=C2=A0xmlXPathRe=
gisterNs on<br>
&gt; ctxt-&gt;xpathCtxt for each nsDef.<br>
<br>
I&#39;m a bit puzzled that this worked at all. See the code here:<br>
<br>
<br>
<a href=3D"https://gitlab.gnome.org/GNOME/libxslt/-/blob/master/libxslt/var=
iables.c#L1581" rel=3D"noreferrer" target=3D"_blank">https://gitlab.gnome.o=
rg/GNOME/libxslt/-/blob/master/libxslt/variables.c#L1581</a></blockquote><d=
iv><br></div><div>=C2=A0I think it works because=C2=A0xsltProcessUserParamI=
nternal only sets</div><div><span>xpctxt</span><span>-&gt;</span><span>name=
spaces =3D NULL but it doesn&#39;t clear xpctxt-&gt;nsHash which is where</=
span></div><div><span>xmlXPathRegisterNs puts the namespaces to be register=
ed.<br></span></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0=
px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br>
<br>
But the expression is compiled before resetting the namespaces, so I guess =
<br>
that&#39;s why.<br>
<br>
&gt; I would have thought this would have been done automatically though.=
=C2=A0 Did I<br>
&gt; miss something or is there a better way to do this?<br>
<br>
No, I&#39;d recommend that you only use string and integer params.<br></blo=
ckquote><div><br></div><div>Can you give me a hint?=C2=A0 =C2=A0I&#39;ve ha=
d absolutely no luck is trying to pass a path</div><div>as a string and get=
ting it to result in something other than &quot;The &#39;select&#39; expres=
sion</div><div>did not evaluate to a node set&quot; even in an absurdly=C2=
=A0simple example.=C2=A0 I&#39;m passing</div><div>the path double quoted &=
quot;&#39;/dm:device&#39;&quot; and have tried various combinations of</div=
><div>&quot;select=3D&quot; and &quot;with-param&quot;.=C2=A0 =C2=A0 Even G=
oogle is failing me so any help would be appreciated.</div><div><br></div><=
div>Thanks!</div><div><br></div><div>=C2=A0</div><blockquote class=3D"gmail=
_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204=
,204);padding-left:1ex">
<br>
Nick<br>
</blockquote></div></div>

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