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Re: [xsl] is XPath 3.1 xml-to-json() function useful

2019-03-08 16:07:11
I've been experimenting with the xml-to-json function, but for some reason
my output is escaped. Why is that?

Stylesheet:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
    xmlns:xs="http://www.w3.org/2001/XMLSchema"; xmlns:f="
http://www.w3.org/2005/xpath-functions"; version="3.0">
    <xsl:output encoding="UTF-8" method="json"/>
    <xsl:template match="/">
        <xsl:variable name="transformed">
            <xsl:apply-templates select="programs"/>
        </xsl:variable>
        <xsl:value-of select="xml-to-json($transformed, map{'indent':
true()})"/>
    </xsl:template>

    <xsl:template match="programs">
        <f:array>
            <xsl:apply-templates select="program"/>
        </f:array>
    </xsl:template>

    <xsl:template match="program">
        <f:map>
            <f:string key="title">
                <xsl:value-of select="@title"/>
            </f:string>
        </f:map>
    </xsl:template>
</xsl:stylesheet>

input:

<programs>
   <program title="ben hur"/>
</programs>

returns:

"[ \n    { \"title    \" : \"ben hur\" } ]"

Running  this with Saxon 9.8 using Oxygen.



On Fri, Mar 8, 2019 at 1:00 PM David Maus lists(_at_)dmaus(_dot_)name <
xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

On Fri, 08 Mar 2019 12:49:28 +0100,
Mukul Gandhi gandhi(_dot_)mukul(_at_)gmail(_dot_)com wrote:

[1  <text/plain; UTF-8 (7bit)>]
[2  <text/html; UTF-8 (quoted-printable)>]
Hi all,

   I find the XPath 3.1 function json-to-xml() quite useful. It can
   convert any JSON input to an XML representation. But I'm not
   convinced that XPath 3.1's xml-to-json() function (as defined in
   the spec) is much useful.

It is very useful to me because it gives full control over the JSON
output.

At work we recently started to publish descriptions of digital objects
as IIIF Manifests [1]. IIIF Manifest is a JSON-based metadata format,
the source of the object descriptions is in XML.

Example: Manuscript Cod. Guelf. 35 Helmst.

XML:
https://github.com/dmj/diglib-iiif/blob/master/examples/mss/35-helmst/mets.xml
JSON: http://iiif.hab.de/object/mss_35-helmst/manifest.json
XSL:
https://github.com/dmj/diglib-iiif/blob/master/src/IIIF/Mapper/METS2IIIFv2.xsl

Not sure if a 'generic' XML to JSON conversion would be of much
help. Being explicit about the JSON structure makes the transformation
manageable.

Best,
  -- David


Taking an example from XPath 3.1 F&O spec, the following XML document

<array xmlns="http://www.w3.org/2005/xpath-functions
"><number>1</number><string>is</string><boolean>1</boolean></array>

converts into following JSON by the function xml-to-json(),

[1,"is",true]

(which is fine)

But as per the XPath 3.1 F&O spec, simple XML documents like,

<root>
   <val>1</val>
   <val>2</val>
   <val>3</val>
   <val>4</val>
</root>

cannot be converted into JSON, by the function xml-to-json(), since the
XML input doesn't conform to structure like <array>, <number>, <string> etc
(which looks to me, a very limited capability given to the xml-to-json()
function).

Any comments would be useful.

--
Regards,
Mukul Gandhi

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David Maus M.A.

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