New subject: Minimal example of lxml writing an XML file and then reading and validating it against an XSD

14 Dec 2011

      Hi,

My name is Duane Kaufman, and I am new to this list (please be gentle :)

I am new to XML (not to Python), and I am wrestling with trying to get
lxml to perform a task for me (I am on Windows XP, Python 2.7 lxml 2.3).

I want to:

1) Use lxml to create an XML file
2) (Manually) create an XML Schema (XSD) file for the created XML file
3) Use lxml to read the XML file, validating it against the XSD file
from 2)

I have tried:
MyXMLWriter.py:
#-------------------------
ScriptRootDir = r'H:\My
Documents\Manufacturing\my_python\XML_Test\XMLSchema_test'

def main():
    global ScriptRootDir
    # Script to test the use of package lxml to pass XML messages
containing data
    # This script will write out an XML file which will be a message
with data
    from lxml import objectify
    from lxml import etree
    import os
    root = objectify.Element("root")
    root.StationName = objectify.DataElement("BaseDispensing",
_xsi="string")
    root.MessageType = objectify.DataElement("BasePartUnloadedData",
_xsi="string")
    objectify.deannotate(root, xsi=False)
    print(etree.tostring(root, pretty_print=True, xml_declaration=True))
    et = etree.ElementTree(root)
    fp = open(os.path.join(ScriptRootDir, "Test.xml"), "w")
    et.write(fp, pretty_print=True, xml_declaration=True)
    fp.close()

if __name__ == '__main__':
    main()
#------------------------

Output from MyXMLWriter.py (Test.xml):
#------------------------
<?xml version='1.0' encoding='ASCII'?>
http://codespeak.net/lxml/objectify/pytype":xsd="http://www.w3
.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <StationName xsi:type="xsd:string">BaseDispensing</StationName>
  <MessageType xsi:type="xsd:string">BasePartUnloadedData</MessageType>
</root>
#-----------------------

Test.xsd:
#------------------
http://www.w3.org/2001/XMLSchema">

#------------------

MyXMLReader.py:
#------------------
ScriptRootDir = r'H:\My
Documents\Manufacturing\my_python\XML_Test\XMLSchema_test'
XMLSchemaFilename = "Test2.xsd"

def main():
    global ScriptRootDir
    # Script to test the use of package lxml to pass XML messages
containing data
    # This script will read in an XML file which will be a message with
data
    # into a Python data structure
    from lxml import etree
    import os

    # read and parse XML Schema file
    xsd_doc = etree.parse(XMLSchemaFilename)
    xsd = etree.XMLSchema(xsd_doc)

    MessageObject = etree.parse(os.path.join(ScriptRootDir, "Test.xml"))
    xsd.validate(MessageObject)
    print xsd.error_log

if __name__ == '__main__':
    main()
#------------------------

When running MyXMLReader.py, I get the output:
file:///H:/My%20Documents/Manufacturing/my_python/XML_Test/XMLSchema_tes
t/Test.xml:1:0:ERROR:SCHEMASV:SCHEMAV_CVC_ELT_1: Element 'root': No
matching global declaration available for the validation root.

How do I get this to work from end-to-end?

Thanks in advance,
Duane

Minimal example of lxml writing an XML file and then reading and validating it against an XSD

Duane Kaufman

Stefan Behnel

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