An XML Schema validator and decoder
xmlschema
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.. xmlschema-introduction-start
The xmlschema library is an implementation of XML Schema <http://www.w3.org/2001/XMLSchema>
_
for Python (supports Python 3.7+).
This library arises from the needs of a solid Python layer for processing XML
Schema based files for
MaX (Materials design at the Exascale) <http://www.max-centre.eu>
_ European project.
A significant problem is the encoding and the decoding of the XML data files
produced by different simulation software.
Another important requirement is the XML data validation, in order to put the
produced data under control. The lack of a suitable alternative for Python in
the schema-based decoding of XML data has led to build this library. Obviously
this library can be useful for other cases related to XML Schema based processing,
not only for the original scope.
The full xmlschema documentation is available on "Read the Docs" <http://xmlschema.readthedocs.io/en/latest/>
_.
This library includes the following features:
You can install the library with pip in a Python 3.7+ environment::
pip install xmlschema
The library uses the Python's ElementTree XML library and requires
elementpath <https://github.com/brunato/elementpath>
_ additional package.
The base schemas of the XSD standards are included in the package for working
offline and to speed-up the building of schema instances.
.. xmlschema-introduction-end
Import the library and then create a schema instance using the path of the file containing the schema as argument:
.. code-block:: pycon
>>> import xmlschema
>>> my_schema = xmlschema.XMLSchema('tests/test_cases/examples/vehicles/vehicles.xsd')
.. note::
For XSD 1.1 schemas use the class XMLSchema11
, because the default class
XMLSchema
is an alias of the XSD 1.0 validator class XMLSchema10
.
The schema can be used to validate XML documents:
.. code-block:: pycon
>>> my_schema.is_valid('tests/test_cases/examples/vehicles/vehicles.xml')
True
>>> my_schema.is_valid('tests/test_cases/examples/vehicles/vehicles-1_error.xml')
False
>>> my_schema.validate('tests/test_cases/examples/vehicles/vehicles-1_error.xml')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/brunato/Development/projects/xmlschema/xmlschema/validators/xsdbase.py", line 393, in validate
raise error
xmlschema.validators.exceptions.XMLSchemaValidationError: failed validating <Element '{http://example.com/vehicles}cars' at 0x7f8032768458> with XsdGroup(model='sequence').
Reason: character data between child elements not allowed!
Schema:
<xs:sequence xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element maxOccurs="unbounded" minOccurs="0" name="car" type="vh:vehicleType" />
</xs:sequence>
Instance:
<vh:cars xmlns:vh="http://example.com/vehicles">
NOT ALLOWED CHARACTER DATA
<vh:car make="Porsche" model="911" />
<vh:car make="Porsche" model="911" />
</vh:cars>
Using a schema you can also decode the XML documents to nested dictionaries, with values that match to the data types declared by the schema:
.. code-block:: pycon
>>> import xmlschema
>>> from pprint import pprint
>>> xs = xmlschema.XMLSchema('tests/test_cases/examples/collection/collection.xsd')
>>> pprint(xs.to_dict('tests/test_cases/examples/collection/collection.xml'))
{'@xsi:schemaLocation': 'http://example.com/ns/collection collection.xsd',
'object': [{'@available': True,
'@id': 'b0836217462',
'author': {'@id': 'PAR',
'born': '1841-02-25',
'dead': '1919-12-03',
'name': 'Pierre-Auguste Renoir',
'qualification': 'painter'},
'estimation': Decimal('10000.00'),
'position': 1,
'title': 'The Umbrellas',
'year': '1886'},
{'@available': True,
'@id': 'b0836217463',
'author': {'@id': 'JM',
'born': '1893-04-20',
'dead': '1983-12-25',
'name': 'Joan MirĂ³',
'qualification': 'painter, sculptor and ceramicist'},
'position': 2,
'title': None,
'year': '1925'}]}
Davide Brunato and others who have contributed with code or with sample cases.
This software is distributed under the terms of the MIT License. See the file 'LICENSE' in the root directory of the present distribution, or http://opensource.org/licenses/MIT.