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Validate XML against schemas found at schemaLocations.
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# coding: utf-8 | |
""" | |
XML Validation by schemaLocation | |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
This snippet addresses the problem of validating XML documents that refer to | |
schemas using xsi:schemaLocation with lxml. The problem has been brought up | |
in the following locations: | |
http://stackoverflow.com/questions/2979824/in-document-schema-declarations-and-lxml | |
https://mailman-mail5.webfaction.com/pipermail/lxml/2011-September/006153.html | |
:copyright: Copright 2013 Mathias Loesch | |
""" | |
from lxml import etree | |
XSI = "http://www.w3.org/2001/XMLSchema-instance" | |
XS = '{http://www.w3.org/2001/XMLSchema}' | |
SCHEMA_TEMPLATE = """<?xml version = "1.0" encoding = "UTF-8"?> | |
<xs:schema xmlns="http://dummy.libxml2.validator" | |
targetNamespace="http://dummy.libxml2.validator" | |
xmlns:xs="http://www.w3.org/2001/XMLSchema" | |
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" | |
version="1.0" | |
elementFormDefault="qualified" | |
attributeFormDefault="unqualified"> | |
</xs:schema>""" | |
def validate_XML(xml): | |
"""Validate an XML file represented as string. Follow all schemaLocations. | |
:param xml: XML represented as string. | |
:type xml: str | |
""" | |
tree = etree.XML(xml) | |
schema_tree = etree.XML(SCHEMA_TEMPLATE) | |
# Find all unique instances of 'xsi:schemaLocation="<namespace> <path-to-schema.xsd> ..."' | |
schema_locations = set(tree.xpath("//*/@xsi:schemaLocation", namespaces={'xsi': XSI})) | |
for schema_location in schema_locations: | |
# Split namespaces and schema locations ; use strip to remove leading | |
# and trailing whitespace. | |
namespaces_locations = schema_location.strip().split() | |
# Import all found namspace/schema location pairs | |
for namespace, location in zip(*[iter(namespaces_locations)] * 2): | |
xs_import = etree.Element(XS + "import") | |
xs_import.attrib['namespace'] = namespace | |
xs_import.attrib['schemaLocation'] = location | |
schema_tree.append(xs_import) | |
# Contstruct the schema | |
schema = etree.XMLSchema(schema_tree) | |
# Validate! | |
schema.assertValid(tree) |
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