lxml - The Python XML Toolkit June 2022

lxml@python.org

6 participants
10 discussions

[lxml-dev] Reparenting a node
by Lawrence Oluyede 30 Jan '23

30 Jan '23

I have a doc A and a doc B, I'd like to put a node extracted from A in the document B but I always get a ValueError: ValueError: Element is not a child of this node. I didn't find any "setparent" in the API. How can I do this? -- Lawrence, oluyede.org - neropercaso.it "It is difficult to get a man to understand something when his salary depends on not understanding it" - Upton Sinclair

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[lxml-dev] Checking whether a node is a comment/element
by Geoffrey Sneddon 11 Jan '23

11 Jan '23

Hi, What's the best way to check whether a given node is a comment or an element? For the former, I'm currently using isinstance(node, etree._Comment), which is rather obviously sub-optimal. -- Geoffrey Sneddon <http://gsnedders.com/>

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[lxml-dev] lxml 2.0.5 released
by Stefan Behnel 11 Jan '23

11 Jan '23

Hi all, lxml 2.0.5 is on PyPI. This is a bug-fix-only release of the stable 2.0 series. Have fun, Stefan 2.0.5 (2008-05-01) Bugs fixed * Resolving to a filename in custom resolvers didn't work. * lxml did not honour libxslt's second error state "STOPPED", which let some XSLT errors pass silently. * Memory leak in Schematron with libxml2 >= 2.6.31.

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Question about inheritance in cssselect.py
by Dani Litovsky Alcala 23 Dec '22

23 Dec '22

lxml v.4.9 cssselect.py:CSSSelector.__init__ calls on `etree.XPath.__init__(self, path, namespaces=namespaces)` to initialize the parent class. Is there a reason why `super()` or even `super(CSSSelector, self)__init__...` is not used? I bring this up as if I attempt to monkey patch (private project) `etree.XPath.__init__` the current code causes an error ``` TypeError: super(type, obj): obj must be an instance or subtype of type ``` while replacing it with the suggested use of `super()` fixes my error.

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[lxml-dev] lxml has its page on launchpad
by Stefan Behnel 21 Sep '22

21 Sep '22

Hi all, I added the lxml project to launchpad, the Ubuntu Bug-Tracker. It also has a FAQ engine and a couple of other goodies. https://launchpad.net/lxml It's easy to sign up for launchpad, BTW, no 90%-footnotes-contract. Have fun, Stefan

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[lxml-dev] Building LXML Trunk
by Sidnei da Silva 31 Aug '22

31 Aug '22

Hi, I've tried to build lxml from trunk today, on Win32. Got the following error: src\lxml\etree.c(880) : error C2059: syntax error : ')' src\lxml\etree.c(881) : error C2059: syntax error : ')' src\lxml\etree.c(882) : error C2059: syntax error : ')' src\lxml\etree.c(883) : error C2059: syntax error : ')' Any clue? Smells like a Pyrex issue? -- Sidnei da Silva Enfold Systems http://enfoldsystems.com Fax +1 832 201 8856 Office +1 713 942 2377 Ext 214

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Tested value modified in validation error message
by Bob Kline 16 Jul '22

16 Jul '22

Before I file a ticket, I wanted to check here to find out if this is a known problem (I searched the bug tracker, but didn't see any matches). Our customer is using a commercial XML editor and the editor's implementation of the DOM API sometimes garbles whitespace inside text nodes when serializing XML documents for the document's xml property. This causes schema validation errors when we send that serialization off to be validated against the document type's schema using lxml. The problem we have run into with lxml is that the message property of the error object which comes back in the schema object's error_log has altered the value being validated. So, for example, if the text content of an element in the serialized DOM is "Processing\ncomplete" and the value it was supposed to match in the enumerated valid values is "Processing complete" then the message attribute for the corresponding object in the error_log has Element 'ProcessingStatusValue': [facet 'enumeration'] The value 'Processing complete' is not an element of the set {'Ready for English peer review', 'Ready for English scientific review', 'Ready for English OCCM review', 'Ready for Spanish peer review', 'Ready for Spanish OCCM review', 'Ready for publishing', 'Ready for translation', 'Processing complete'}. In effect saying "the value 'Processing complete' does not match the value 'Processing complete'." Took a very long time for us to figure out that the error message was wrong, and that it should have said ... The value 'Processing\ncomplete' is not an element of the set .... -- Bob Kline https://www.rksystems.com mailto:bkline@rksystems.com

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Iterparse raises TypeError on attempt to clean up preceding siblings
by Parfait Gasana 26 Jun '22

26 Jun '22

Hello, While following the iterparse / modifying the tree docs (https://lxml.de/4.5/parsing.html#modifying-the-tree) in attempt to clean up preceding siblings, code raises a TypeError: 'NoneType' object does not support item deletion when the XML contains a comment preceding the root element. Please advise on a workaround for this use case if this is not a potential bug. See below reproducible example. Thank you for your time and review. ```python from io import BytesIO import lxml.etree as ET xml_txt = '''\  <issue> <type>BUG</type> </issue> '''.encode('utf-8') iterparse_columns = { "issue": ["type"] } data = [] for event, elem in ET.iterparse(BytesIO(xml_txt), events=('start', 'end')): node = next(iter(iterparse_columns)) curr_elem = ( elem.tag.split('}')[1] if '}' in elem.tag else elem.tag ) if event == 'start': if curr_elem == node: row = {} for col in iterparse_columns[node]: if curr_elem == col: row[col] = ( elem.text.strip() if elem.text is not None else elem.text ) if col in elem.attrib: row[col] = elem.attrib[col].strip() if event == 'end': if curr_elem == node: data.append(row) elem.clear() while elem.getprevious() is not None: del elem.getparent()[0] print(data) ``` Full traceback: ``` Traceback (most recent call last): File "iterparse_parent_comment_reprex.py", line 43, in <module> del elem.getparent()[0] TypeError: 'NoneType' object does not support item deletion ```

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tostring() returning possible invalid XML. Is this a bug?
by brian.bird＠trustpayments.com 07 Jun '22

07 Jun '22

In more recent versions of lxml the tostring() method can return extra text after the closing tag of the node I've passed to it. So instead of returning b'<form action="action1">\n</form>\n' it returns b'<form action="action1">\n</form>\n</body>\n</html>\n' Here's a (python3) script along with two outputs, one from a machine running lxml 4.6.5 and one running 4.8.0. NOTE the output only changes if the DOCTYPE line is left in the "html" variable. import sys from lxml import etree print("%-20s: %s" % ('Python', sys.version_info)) print("%-20s: %s" % ('lxml.etree', etree.LXML_VERSION)) print("%-20s: %s" % ('libxml used', etree.LIBXML_VERSION)) print("%-20s: %s" % ('libxml compiled', etree.LIBXML_COMPILED_VERSION)) print("%-20s: %s" % ('libxslt used', etree.LIBXSLT_VERSION)) print("%-20s: %s" % ('libxslt compiled', etree.LIBXSLT_COMPILED_VERSION)) html = """<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html> <body> <form action="action1"> </form> </body> </html> """ parser = etree.XMLParser() doc = etree.fromstring(html, parser=parser) nodeList = doc.xpath("//form") print(etree.tostring(nodeList[0])) This is the output I would expect to see: Python : sys.version_info(major=3, minor=8, micro=10, releaselevel='final', serial=0) lxml.etree : (4, 6, 5, 0) libxml used : (2, 9, 10) libxml compiled : (2, 9, 10) libxslt used : (1, 1, 34) libxslt compiled : (1, 1, 34) b'<form action="action1">\n</form>\n' #<------ Notice how the tostring() has returned the opening and closing <form> node (as I expected) This is the output I get when I upgrade: Python : sys.version_info(major=3, minor=8, micro=10, releaselevel='final', serial=0) lxml.etree : (4, 8, 0, 0) libxml used : (2, 9, 12) libxml compiled : (2, 9, 12) libxslt used : (1, 1, 34) libxslt compiled : (1, 1, 34) b'<form action="action1">\n</form>\n</body>\n</html>\n' #<-------- Notice how the tostring() has returned extra text after the closing </form> tag Is this a bug? Or is this expected behaviour if the DOCTYPE is defined in the html passed to etree.fromstring()? ie. Is there a valid reason why tostring() might return an invalid XML byte string? I've seen the same behaviour in lxml 4.7.1 but I've not tried 4.9.0 as it's not in my repo yet. Any help appreciated! If this is a deliberate change I've got quite a lot of legacy code that will need updating to cope.

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Build problems on Python 3.11
by Charlie Clark 01 Jun '22

01 Jun '22

Hi, while I don't see this locally, I'm getting problems on my CI with the Docker Image: ``` Compile failed: command '/usr/bin/gcc' failed with exit code 1 cc -I/usr/include/libxml2 -I/usr/include/libxml2 -c /tmp/xmlXPathInitw7u6s7rr.c -o tmp/xmlXPathInitw7u6s7rr.o cc tmp/xmlXPathInitw7u6s7rr.o -lxml2 -o a.out error: command '/usr/bin/gcc' failed with exit code 1 [end of output] note: This error originates from a subprocess, and is likely not a problem with pip. error: legacy-install-failure × Encountered error while trying to install package. ╰─> lxml ``` I'm wondering if there is anything that can be done about this? Presumably inform the maintainer? Charlie -- Charlie Clark Managing Director Clark Consulting & Research German Office Sengelsweg 34 Düsseldorf D- 40489 Tel: +49-203-3925-0390 Mobile: +49-178-782-6226

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lxml - The Python XML Toolkit June 2022