Using XSLT to transform XML to JSON - json

Question

I would like to use XSLT to transform some XML into JSON.
The XML looks like the following:
<DATA_DS>
<G_1>
<ORGANIZATION_NAME>My Company 1</ORGANIZATION_NAME>
<ORGANIZATIONID>901</ORGANIZATIONID>
<ITEMNUMBER>20001</ITEMNUMBER>
<ITEMDESCRIPTION>Item Description 1</ITEMDESCRIPTION>
</G_1>
<G_1>
<ORGANIZATION_NAME>My Company 1</ORGANIZATION_NAME>
<ORGANIZATIONID>901</ORGANIZATIONID>
<ITEMNUMBER>20002</ITEMNUMBER>
<ITEMDESCRIPTION>Item Description 2</ITEMDESCRIPTION>
</G_1>
<G_1>
<ORGANIZATION_NAME>My Company 1</ORGANIZATION_NAME>
<ORGANIZATIONID>901</ORGANIZATIONID>
<ITEMNUMBER>20003</ITEMNUMBER>
<ITEMDESCRIPTION>Item Description 3</ITEMDESCRIPTION>
</G_1>
</DATA_DS>
I expect the JSON to look like the following:
[
{
"Item_Number":"20001",
"Item_Description":"Item Description 1"
},
{
"Item_Number":"20002",
"Item_Description":"Item Description 2"
},
{
"Item_Number":"20003",
"Item_Description":"Item Description 3"
}
]
What is the recommended way to do this?
I am considering two approaches:
Try using the fn:xml-to-json function, as defined at https://www.w3.org/TR/xpath-functions-31/#func-xml-to-json. But as I understand, the input XML must follow a specific format defined at: https://www.w3.org/TR/xpath-functions-31/schema-for-json.xsd. And I also need the field names in the output JSON to be specifically "Item_Number" and "Item_Description".
Manually code the bracket and brace characters, "[", "]", "{", and "}", along with the field names "Item_Number" and "Item_Description". Then use a standard function to list the values and ensure that any special characters are handled properly. For example, the "&" character should appear normally in the JSON output.
What is the recommended way to do this, or is there a better way that I have not considered?

Answer 1

I would take the first approach, but start with transforming the given input to the XML format expected by the xml-to-json() function. This could be something like:
XSLT 3.0
<xsl:stylesheet version="3.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns="http://www.w3.org/2005/xpath-functions">
<xsl:output method="text" encoding="UTF-8"/>
<xsl:template match="/G_1">
<!-- CONVERT INPUT TO XML FOR JSON -->
<xsl:variable name="xml">
<array>
<xsl:for-each-group select="*" group-starting-with="ORGANIZATION_NAME">
<map>
<string key="Item_Number">
<xsl:value-of select="current-group()[self::ITEMNUMBER]"/>
</string>
<string key="Item_Description">
<xsl:value-of select="current-group()[self::ITEMDESCRIPTION]"/>
</string>
</map>
</xsl:for-each-group>
</array>
</xsl:variable>
<!-- OUTPUT -->
<xsl:value-of select="xml-to-json($xml)"/>
</xsl:template>
</xsl:stylesheet>
Demo: https://xsltfiddle.liberty-development.net/bFWR5DQ

Answer 2

For simple mappings like that you can also directly construct XPath 3.1 arrays and maps i.e. in this case an array of maps:
<xsl:template match="DATA_DS">
<xsl:sequence select="array { G_1 ! map { 'Item_Number' : string(ITEMNUMBER), 'Item_Description' : string(ITEMDESCRIPTION) } }"/>
</xsl:template>
Then serialize as JSON with <xsl:output method="json" indent="yes"/>: https://xsltfiddle.liberty-development.net/ejivdGS
The main disadvantage is that maps have no order so you can't control the order of the items in a map, for instance for that example and the used Saxon version Item_Description is output before Item_Number.
But in general transforming to the format for xml-to-json provides more flexibility and also allows you to control the order as the function preserves the order in the XML representation of JSON.

Answer 3

This is the result of taking the solution posted by michael.hor257k and applying it to my revised input XML:
<xsl:stylesheet version="3.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns="http://www.w3.org/2005/xpath-functions">
<xsl:output method="text" encoding="UTF-8"/>
<xsl:template match="/DATA_DS">
<!-- CONVERT INPUT TO XML FOR JSON -->
<xsl:variable name="xml">
<array>
<xsl:for-each select="G_1">
<map>
<string key="Item_Number">
<xsl:value-of select="ITEMNUMBER"/>
</string>
<string key="Item_Description">
<xsl:value-of select="ITEMDESCRIPTION"/>
</string>
</map>
</xsl:for-each>
</array>
</xsl:variable>
<!-- OUTPUT -->
<xsl:value-of select="xml-to-json($xml)"/>
</xsl:template>
</xsl:stylesheet>