* Request for xml.filter explanation!
@ 2019-04-10 19:27 Geert Verhaag
2019-04-11 15:33 ` Hans Hagen
0 siblings, 1 reply; 2+ messages in thread
From: Geert Verhaag @ 2019-04-10 19:27 UTC (permalink / raw)
To: ntg-context
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Hi,
I've the following xml file:
*<?xml version='1.0' standalone='yes?>
<content>
<object mid="a">
<text>a paragraph of text</text>
<value>40.2</value>
</object>
<object mid="b">
<text>another paragraph of text</text>
<value>10.7</value>
</object>
<object mid="c">
<text>still another paragraph!</text>
<value>20.5</value>
</object>
</content>*
And want to calculate the total value of all the objects:
like so:
*\startxmlsetups xml:example:base
\xmlsetsetup{#1}{content|object}{xml:example:*}
\stopxmlsetups
\xmlregisterdocumentsetup{example}{xml:example:base}
\startxmlsetups xml:example:content
totalvalue: \xmlfunction{#1}{totalvalue}
\xmlflush{#1} \endgraf
\stopxmlsetups
\startxmlsetups xml:example:object
attribute : \xmlatt{#1}{mid} \par
\stopxmlsetups
% LUA
\startluacode
function xml.functions.totalvalue(root)
local score = 0
for e in xml.collected(root,"/object") do
tex.write('Okay!')
--score = score + xml.filter(e,"xml:///value/number()") or 0
end
tex.write(score)
end
\stopluacode
\starttext
\xmlprocessfile{example}{content.xml}{}
\stoptext*
*
*
When I run this example I get:
*totalvalue: Okay!Okay!Okay!0 attribute : a
attribute : b
attribute : c*
That looks allright!
But when I incorporate the line:
*score = score + xml.filter(e,"xml:///value/number()") or 0*
the following Lua error is thrown:
**
*! LuaTeX error [string "\directlua "]:5: attempt to perform arithmetic
on a nil value*
Has anybody any idea what I'm doing wrong here? The manual
*xml-mkiv.pdf* doesn't give any clue about this!
Regards,
Gerard
--
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___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!
maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Request for xml.filter explanation!
2019-04-10 19:27 Request for xml.filter explanation! Geert Verhaag
@ 2019-04-11 15:33 ` Hans Hagen
0 siblings, 0 replies; 2+ messages in thread
From: Hans Hagen @ 2019-04-11 15:33 UTC (permalink / raw)
To: Geert Verhaag, mailing list for ConTeXt users
On 4/10/2019 9:27 PM, Geert Verhaag wrote:
> Hi,
>
> I've the following xml file:
>
> *<?xml version='1.0' standalone='yes?>
>
> <content>
> <object mid="a">
> <text>a paragraph of text</text>
> <value>40.2</value>
> </object>
> <object mid="b">
> <text>another paragraph of text</text>
> <value>10.7</value>
> </object>
> <object mid="c">
> <text>still another paragraph!</text>
> <value>20.5</value>
> </object>
> </content>*
>
> And want to calculate the total value of all the objects:
>
> like so:
>
> *\startxmlsetups xml:example:base
> \xmlsetsetup{#1}{content|object}{xml:example:*}
> \stopxmlsetups
>
> \xmlregisterdocumentsetup{example}{xml:example:base}
>
> \startxmlsetups xml:example:content
> totalvalue: \xmlfunction{#1}{totalvalue}
> \xmlflush{#1} \endgraf
> \stopxmlsetups
>
> \startxmlsetups xml:example:object
> attribute : \xmlatt{#1}{mid} \par
> \stopxmlsetups
>
> % LUA
>
> \startluacode
> function xml.functions.totalvalue(root)
> local score = 0
> for e in xml.collected(root,"/object") do
> tex.write('Okay!')
> --score = score + xml.filter(e,"xml:///value/number()") or 0
> end
> tex.write(score)
> end
> \stopluacode
>
> \starttext
>
> \xmlprocessfile{example}{content.xml}{}
>
> \stoptext*
>
> *
> *
>
> When I run this example I get:
>
> *totalvalue: Okay!Okay!Okay!0 attribute : a
> attribute : b
> attribute : c*
>
> That looks allright!
>
> But when I incorporate the line:
>
> *score = score + xml.filter(e,"xml:///value/number()") or 0*
>
> the following Lua error is thrown:
> **
>
> *! LuaTeX error [string "\directlua "]:5: attempt to perform arithmetic
> on a nil value*
>
> Has anybody any idea what I'm doing wrong here? The manual
> *xml-mkiv.pdf* doesn't give any clue about this!
\startluacode
function xml.functions.totalvalue(root)
local score = 0
for e in xml.collected(root,"/object/value") do
score = score + tonumber(xml.text(e)) or 0
end
context(score)
end
\stopluacode
-----------------------------------------------------------------
Hans Hagen | PRAGMA ADE
Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!
maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage : http://www.pragma-ade.nl / http://context.aanhet.net
archive : https://bitbucket.org/phg/context-mirror/commits/
wiki : http://contextgarden.net
___________________________________________________________________________________
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