XSLT: convert XML to JSON creating a group of sub nodes - json

Question

it's been days trying to perform a transformation to get a JSON file from XML documents. My xml doc have different levels of sub nodes, all examples I found on internet don't catch my case.
Here is my xml example:
<?xml version="1.0" encoding="UTF-8"?>
<root>
<foo id="1" group="B" />
<foo id="2" group="A" />
<foo id="3", group="A">
<foo id="4" group="A" />
<foo id="5" group="A">
<foo id="6" group="A" />
<foo id="7" group="A" />
<foo id="8" group="A" />
</foo>
</foo>
<foo id="9" group="A"></foo>
</root>
desired JSON:
{
"B": {
"id": 1
},
"A": {
"id": 2
},
"A": [{
"id": 4
},
{
"A": [{
"id": 6
},
{
"id": 7
},
{
"id": 8
}
]
}
],
"A": {
"id": 9
}
}
Means whenever I have nested <foo> elements, child elements are grouped with the parent element, and so on.
I tried some xsl code (see1 and see2) and failed to make them work for my case.

Answer 1

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
exclude-result-prefixes="xs"
version="2.0">
<xsl:strip-space elements="*"/>
<xsl:output method="xml" indent="yes"/>
<xsl:template match="root">
<xsl:text>{</xsl:text>
<xsl:apply-templates select="//foo"/>
<xsl:text>}</xsl:text>
</xsl:template>
<xsl:template match="//foo">
<xsl:choose>
<xsl:when test=" count(ancestor::foo) = 1 and child::foo"/>
<xsl:when test="foo[child::foo]"/>
<xsl:otherwise>
<xsl:text>"</xsl:text><xsl:value-of select="#group"/><xsl:text>"</xsl:text>:<xsl:text> {
</xsl:text>
<xsl:text> "</xsl:text><xsl:value-of select="#id/name()"/><xsl:text>"</xsl:text>:<xsl:value-of select=" concat(' ',#id)"/>
<xsl:text>
},</xsl:text>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
</xsl:stylesheet>

Answer 2

Please Check this code:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema" exclude-result-prefixes="xs" version="2.0">
<xsl:output method="xml" omit-xml-declaration="yes"/>
<xsl:template match="root">
<xsl:text>{</xsl:text>
<xsl:text>
</xsl:text>
<xsl:for-each select="foo">
<xsl:if test="not(child::foo)">
<xsl:text> "</xsl:text><xsl:value-of select="#group"/><xsl:text>": </xsl:text><xsl:text>{</xsl:text><xsl:text>
</xsl:text>
<xsl:text> "id": </xsl:text><xsl:value-of select="#id"/><xsl:text>
</xsl:text>
<xsl:text> }</xsl:text>
<xsl:if test="position()!=last()">
<xsl:text>,</xsl:text>
</xsl:if>
<xsl:text>
</xsl:text>
</xsl:if>
<xsl:for-each select="foo">
<xsl:if test="not(child::foo)">
<xsl:text> "</xsl:text><xsl:value-of select="#group"/><xsl:text>": </xsl:text><xsl:if test="parent::foo"><xsl:text>[</xsl:text></xsl:if><xsl:text>{</xsl:text><xsl:text>
</xsl:text>
<xsl:text> "id": </xsl:text><xsl:value-of select="#id"/><xsl:text>
</xsl:text>
<xsl:text> },</xsl:text><xsl:text>
</xsl:text>
<xsl:text> {</xsl:text><xsl:text>
</xsl:text>
<xsl:text> "</xsl:text><xsl:value-of select="#group"/><xsl:text>": </xsl:text><xsl:text>[</xsl:text><xsl:text>
</xsl:text>
</xsl:if>
<!-- <xsl:text> "</xsl:text><xsl:value-of select="#group"/><xsl:text>": </xsl:text><xsl:text>[{</xsl:text><xsl:text>
</xsl:text>-->
<xsl:for-each select="foo">
<xsl:text> {</xsl:text><xsl:text>
</xsl:text>
<xsl:text> "id": </xsl:text><xsl:value-of select="#id"/><xsl:text>
</xsl:text>
<xsl:text> }</xsl:text>
<xsl:if test="position()!=last()">
<xsl:text>,</xsl:text>
</xsl:if><xsl:text>
</xsl:text>
<xsl:if test="position()=last()">
<xsl:text> ]</xsl:text><xsl:text>
</xsl:text>
</xsl:if>
<xsl:if test="position()=last()">
<xsl:text> }</xsl:text><xsl:text>
</xsl:text>
</xsl:if>
<xsl:if test="position()=last()">
<xsl:text>],</xsl:text><xsl:text>
</xsl:text>
</xsl:if>
<xsl:text>
</xsl:text>
</xsl:for-each>
</xsl:for-each>
</xsl:for-each>
<xsl:text>}</xsl:text>
</xsl:template>
</xsl:stylesheet>

Answer 3

It is not quite clear which result you want as the desired "JSON" has duplicated properties if there are various foo group="A" elements but in general of XML to JSON generation you can use XSLT 3 with support for XPath 3.1 maps and arrays (https://www.w3.org/TR/xpath-31/#id-maps-and-arrays) and the json output method or the xml-to-json function (https://www.w3.org/TR/xslt-30/#json, https://www.w3.org/TR/xslt-30/#func-xml-to-json), that way you have two ways of creating JSON and outputting it, you can either transform your XML directly to XPath 3.1 maps/arrays and serialize them with <xsl:output method="json"/> or you can use the usual XSLT processing to transform your input XML to the JSON XML representation the xml-to-json function expects and apply it to get the JSON as text.
Here is an example of the first approach:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
exclude-result-prefixes="#all"
version="3.0">
<xsl:mode on-no-match="shallow-skip"/>
<xsl:strip-space elements="*"/>
<xsl:output method="json" indent="yes"/>
<xsl:template match="*[*]">
<xsl:map>
<xsl:for-each-group select="foo" group-by="#group">
<xsl:map-entry key="string(current-grouping-key())">
<xsl:choose>
<xsl:when test="not(tail(current-group()))">
<xsl:apply-templates select="current-group()"/>
</xsl:when>
<xsl:otherwise>
<xsl:variable name="group-transform" as="map(*)*">
<xsl:apply-templates select="current-group()"/>
</xsl:variable>
<xsl:sequence select="array { $group-transform }"/>
</xsl:otherwise>
</xsl:choose>
</xsl:map-entry>
</xsl:for-each-group>
</xsl:map>
</xsl:template>
<xsl:template match="*[not(*)]">
<xsl:sequence select="map { 'id' : data(#id) }"/>
</xsl:template>
</xsl:stylesheet>
https://xsltfiddle.liberty-development.net/6r5Gh3i
And here one of the second:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
exclude-result-prefixes="#all"
xmlns="http://www.w3.org/2005/xpath-functions"
expand-text="yes"
version="3.0">
<xsl:mode on-no-match="shallow-skip"/>
<xsl:strip-space elements="*"/>
<xsl:output method="text"/>
<xsl:variable name="json-xml">
<xsl:apply-templates/>
</xsl:variable>
<xsl:template match="/">
<xsl:sequence select="xml-to-json($json-xml, map { 'indent' : true() })"/>
</xsl:template>
<xsl:template match="*[*]">
<map>
<xsl:for-each-group select="foo" group-by="string(#group)">
<xsl:choose>
<xsl:when test="not(tail(current-group()))">
<map key="{current-grouping-key()}">
<string key="id">{#id}</string>
</map>
</xsl:when>
<xsl:otherwise>
<array key="{current-grouping-key()}">
<xsl:apply-templates select="current-group()"/>
</array>
</xsl:otherwise>
</xsl:choose>
</xsl:for-each-group>
</map>
</xsl:template>
<xsl:template match="*[not(*)]">
<map>
<string key="id">{#id}</string>
</map>
</xsl:template>
</xsl:stylesheet>
https://xsltfiddle.liberty-development.net/6r5Gh3i/5
XSLT 3 is available using Saxon 9.8 or 9.9 HE for the Java platform on Sourceforge and Maven https://mvnrepository.com/artifact/net.sf.saxon/Saxon-HE/9.9.1-2 and for the .NET platform on NuGet https://www.nuget.org/packages/Saxon-HE/.