Hi,
I’m not sure if I just overlooked something but it seems that
etree.tostring using method c14n2 does not work in the same way in
Python2 and Python3. In Python2 it works as expected in Python3 it
claims about a not declared namespace which is is still there (see
stdout information in tests).
I put together a simple TestCase class
(https://pastebin.com/raw/fgMjy0Ax) which shows the different behaviour
if invoked for the latest released lxml version 4.6.4 using Python2 or
Python3:
c:\python27\python.exe -m nose ./py3_test.py
....
----------------------------------------------------------------------
Ran 4 tests in 0.014s
OK
c:\python39\python.exe -m nose ./py3_test.py
EEEE
======================================================================
ERROR: test_python3_problem_bytesio_iterparse
(py3_test.LXML_C14N2_RegressionTest)
----------------------------------------------------------------------
Traceback (most recent call last):
File "c:\devel\code\cs.requirements\py3_test.py", line 18, in
test_python3_problem_bytesio_iterparse
handle_div_end(event, element)
File "c:\devel\code\cs.requirements\py3_test.py", line 13, in
handle_div_end
etree.tostring(element, method="c14n2")
File "src\lxml\etree.pyx", line 3407, in lxml.etree.tostring
File "src\lxml\serializer.pxi", line 943, in lxml.etree._tree_to_target
File "src\lxml\serializer.pxi", line 1128, in
lxml.etree.C14NWriterTarget.start
File "src\lxml\serializer.pxi", line 1155, in
lxml.etree.C14NWriterTarget._start
File "src\lxml\serializer.pxi", line 1085, in
lxml.etree.C14NWriterTarget._qname
ValueError: Namespace http://www.w3.org/1999/xhtml of name "div" is not
declared in scope
-------------------- >> begin captured stdout << ---------------------
<class 'str'> <class 'str'> some_ns_id = http://www.example.com
<class 'str'> <class 'str'> xhtml = http://www.w3.org/1999/xhtml
--------------------- >> end captured stdout << ----------------------
======================================================================
ERROR: test_python3_problem_bytesio_iterparse_global_ns_registration
(py3_test.LXML_C14N2_RegressionTest)
----------------------------------------------------------------------
Traceback (most recent call last):
File "c:\devel\code\cs.requirements\py3_test.py", line 34, in
test_python3_problem_bytesio_iterparse_global_ns_registration
handle_div_end(event, element)
File "c:\devel\code\cs.requirements\py3_test.py", line 29, in
handle_div_end
etree.tostring(element, method="c14n2")
File "src\lxml\etree.pyx", line 3407, in lxml.etree.tostring
File "src\lxml\serializer.pxi", line 943, in lxml.etree._tree_to_target
File "src\lxml\serializer.pxi", line 1128, in
lxml.etree.C14NWriterTarget.start
File "src\lxml\serializer.pxi", line 1155, in
lxml.etree.C14NWriterTarget._start
File "src\lxml\serializer.pxi", line 1085, in
lxml.etree.C14NWriterTarget._qname
ValueError: Namespace http://www.w3.org/1999/xhtml of name "div" is not
declared in scope
-------------------- >> begin captured stdout << ---------------------
<class 'str'> <class 'str'> some_ns_id = http://www.example.com
<class 'str'> <class 'str'> xhtml = http://www.w3.org/1999/xhtml
--------------------- >> end captured stdout << ----------------------
======================================================================
ERROR: test_python3_problem_filebased_iterparse
(py3_test.LXML_C14N2_RegressionTest)
----------------------------------------------------------------------
Traceback (most recent call last):
File "c:\devel\code\cs.requirements\py3_test.py", line 49, in
test_python3_problem_filebased_iterparse
handle_div_end(event, element)
File "c:\devel\code\cs.requirements\py3_test.py", line 44, in
handle_div_end
etree.tostring(element, method="c14n2")
File "src\lxml\etree.pyx", line 3407, in lxml.etree.tostring
File "src\lxml\serializer.pxi", line 943, in lxml.etree._tree_to_target
File "src\lxml\serializer.pxi", line 1128, in
lxml.etree.C14NWriterTarget.start
File "src\lxml\serializer.pxi", line 1155, in
lxml.etree.C14NWriterTarget._start
File "src\lxml\serializer.pxi", line 1085, in
lxml.etree.C14NWriterTarget._qname
ValueError: Namespace http://www.w3.org/1999/xhtml of name "div" is not
declared in scope
-------------------- >> begin captured stdout << ---------------------
<class 'str'> <class 'str'> some_ns_id = http://www.example.com
<class 'str'> <class 'str'> xhtml = http://www.w3.org/1999/xhtml
--------------------- >> end captured stdout << ----------------------
======================================================================
ERROR: test_python3_problem_filebased_parse
(py3_test.LXML_C14N2_RegressionTest)
----------------------------------------------------------------------
Traceback (most recent call last):
File "c:\devel\code\cs.requirements\py3_test.py", line 62, in
test_python3_problem_filebased_parse
serialize_div_element(div)
File "c:\devel\code\cs.requirements\py3_test.py", line 58, in
serialize_div_element
etree.tostring(element, method="c14n2")
File "src\lxml\etree.pyx", line 3407, in lxml.etree.tostring
File "src\lxml\serializer.pxi", line 943, in lxml.etree._tree_to_target
File "src\lxml\serializer.pxi", line 1128, in
lxml.etree.C14NWriterTarget.start
File "src\lxml\serializer.pxi", line 1155, in
lxml.etree.C14NWriterTarget._start
File "src\lxml\serializer.pxi", line 1085, in
lxml.etree.C14NWriterTarget._qname
ValueError: Namespace http://www.w3.org/1999/xhtml of name "div" is not
declared in scope
-------------------- >> begin captured stdout << ---------------------
<class 'str'> <class 'str'> some_ns_id = http://www.example.com
<class 'str'> <class 'str'> xhtml = http://www.w3.org/1999/xhtml
--------------------- >> end captured stdout << ----------------------
----------------------------------------------------------------------
Ran 4 tests in 0.010s
FAILED (errors=4)
Could you give me some hint whether this is an actual bug or just a
wrong usage?
If it is a bug – should I create a new one in your bug tracker or will
you add one directly?
Best regards,
Kai
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