xml2

XPath querying and XSLT

https://www.postgresql.org/docs/current/xml2.html

Overview

Package	Version	Category	License	Language
`xml2`	`1.1`	TYPE	PostgreSQL	C

ID	Extension	Bin	Lib	Load	Create	Trust	Reloc	Schema
3990	`xml2`	No	No	No	Yes	No	No	-

Related	`plxslt` `omni_xml` `pgrdf` `sparql` `rdf_fdw` `pgpdf` `pgbson` `hstore` `pglite_fusion`

Version

PG18	PG17	PG16	PG15	PG14
1.1	1.1	1.1	1.1	1.1

Install

Note: This is a built-in contrib extension of PostgreSQL

CREATE EXTENSION xml2;

Usage

xml2: XPath querying and XSLT functionality

The xml2 extension provides XPath querying and XSLT transformation functions for XML documents. Note: this module is deprecated in favor of the core SQL/XML functionality.

CREATE EXTENSION xml2;

XML Validation

SELECT xml_valid('<doc><item>test</item></doc>');  -- true

XPath Query Functions

-- Extract text value
SELECT xpath_string('<doc><name>Alice</name></doc>', '/doc/name');

-- Extract numeric value
SELECT xpath_number('<doc><count>42</count></doc>', '/doc/count');

-- Extract boolean
SELECT xpath_bool('<doc><active>true</active></doc>', '/doc/active');

-- Extract node set with tags
SELECT xpath_nodeset('<doc><a>1</a><a>2</a></doc>', '/doc/a', 'results', 'item');

-- Extract values as comma-separated list
SELECT xpath_list('<doc><a>1</a><a>2</a></doc>', '/doc/a');  -- 1,2

xpath_table Function

Evaluate multiple XPath queries across a set of documents:

SELECT * FROM
  xpath_table('id', 'xml_col', 'documents',
              '/doc/author|/doc/title',
              'true')
  AS t(id int, author text, title text);

Parameters:

Key field name (first output column)
XML document field name
Table/view name
XPath expressions separated by |
WHERE clause (use 'true' for all rows)

XSLT Transformation

-- Apply XSL stylesheet to document
SELECT xslt_process(xml_document, xsl_stylesheet);

-- With parameters
SELECT xslt_process(xml_document, xsl_stylesheet, 'param1=value1,param2=value2');