extracting information from a JSON file using XSLT version 1.0 - json

Question

I'm a noobie to stackoverflow and xslt so I hope I don't sound unintelligent!
So I am working with SDI for a GIS company and I have a task that requires me to convert points that are in one spacial reference system (SRS) coordinate plane, such as EPSG:4035, to the world SRS, aka EPSG:4326. This really isn't a problem for me since I have the accessibility of an online service that will just give me what I want. However, the format that it outputs is in either JSON or HTML. I have browsed for a while to find a way to extract information from a JSON file but most of the techniques I have seen use xslt:stylesheet version 2.0, and I have to use version 1.0. One method I thought about doing was using the document($urlWithJsonFormat) xslt function, however this only accepts xml files.
Here is an example of the JSON formatted file that I would retrieve after asking for the conversion:
{
"geometries" :
[{
"xmin" : -4,
"ymin" : -60,
"xmax" : 25,
"ymax" : -41
}
]
}
All I simply want are the xmin, ymin, xmax, and ymax values, that's all! It just seems so simple yet nothing works for me...

Answer 1

You could use an external entity to include the JSON data as part of an XML file that you then transform.
For instance, assuming the example JSON is saved as a file called "geometries.json" you could create an XML file like this:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE wrapper [
<!ENTITY otherFile SYSTEM "geometries.json">
]>
<wrapper>&otherFile;</wrapper>
And then transform it with the following XSLT 1.0 stylesheet:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:template match="wrapper">
<geometries>
<xsl:call-template name="parse-json-member-value">
<xsl:with-param name="member" select="'xmin'"/>
</xsl:call-template>
<xsl:call-template name="parse-json-member-value">
<xsl:with-param name="member" select="'ymin'"/>
</xsl:call-template>
<xsl:call-template name="parse-json-member-value">
<xsl:with-param name="member" select="'xmax'"/>
</xsl:call-template>
<xsl:call-template name="parse-json-member-value">
<xsl:with-param name="member" select="'ymax'"/>
</xsl:call-template>
</geometries>
</xsl:template>
<xsl:template name="parse-json-member-value">
<xsl:param name="member"/>
<xsl:element name="{$member}">
<xsl:value-of select="normalize-space(
translate(
substring-before(
substring-after(
substring-after(.,
concat('"',
$member,
'"'))
, ':')
,'
')
, ',', '')
)"/>
</xsl:element>
</xsl:template>
</xsl:stylesheet>
To produce the following output:
<geometries>
<xmin>-4</xmin>
<ymin>-60</ymin>
<xmax>25</xmax>
<ymax>-41</ymax>
</geometries>

Answer 2

The two main choices here seem to be:
write (or use) a JSON parser in XSLT 1.0, or
use some other language than XSLT.
Since XSLT 1 engines generally can't process JSON directly I'd recommend using some other language to convert to XML.
https://github.com/WelcomWeb/JXS may help you too, if this is XSLT in a Web browser.