lxml - The Python XML Toolkit September 2021

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4 participants
12 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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[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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[newbie] Easier way to check if element exists, edit if exists, insert if not?
by Gilles 17 Sep '21

17 Sep '21

Hello, Out of curiosity, is there a more compact way to check if an element exists, edit if it does, insert if it doesn't ? #=========== Edit/insert top-most name r = root.find('./Document/name') #if et.iselement(r) if r is not None: print("Name exists: ",r.text) r.text = BASENAME else: print("Name does not exist") #insert new element et.SubElement('/kml/Document', "name").text = BASENAME Thank you.

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Re: lxml.objectify interprets <x>1000_000</x> as int in Python>3.6 - should it?
by Holger.Joukl＠LBBW.de 14 Sep '21

14 Sep '21

> > [...] > > 0 $ (PYTHONPATH=build/lib.linux-x86_64-3.6/ python3 -m timeit -r 5 -n > > 1000000 --setup 'from lxml import etree, objectify' 'root = > > objectify.XML("<root><x>1000000</x><y>1000_000</y></root>")') > > 1000000 loops, best of 5: 17.1 usec per loop > > > > (No it's not faster, this is just a lucky timeit run - but it's > > absolutely in the same ballpark as before) > > … except that this is not a good benchmark – it doesn't call the code that was > changed. :) Oh boy. Yes of course :-/, thanks for noting. > You could use `objectify.XML("…").y' to get an actual element tested and > instantiated. > > I wouldn't expect much of a difference, though. Parsing will take most of the time, > then actually instantiating the element object. Testing the value should be quick in > comparison (and even quicker now). $ (for PYTHONPATH in "$LXML462" "$TRUNK"; do (export PYTHONPATH; python3 -c'from lxml import etree, objectify; print(etree.__version__); root = objectify.XML("<root><x>1000_000.123</x><y>1000_000</y><z>1000_000_</z></root>"); print(objectify.dump(root))'); echo; done;) 4.6.2 root = None [ObjectifiedElement] x = 1000000.123 [FloatElement] y = 1000000 [IntElement] z = '1000_000_' [StringElement] 4.6.3 root = None [ObjectifiedElement] x = '1000_000.123' [StringElement] y = '1000_000' [StringElement] z = '1000_000_' [StringElement] $ (for EXPR in root.x root.y root.z; do echo "=== $EXPR"; for PYTHONPATH in "$LXML462" "$TRUNK"; do (export PYTHONPATH; python3 -c'from lxml import etree; print(etree.__version__)'; python3 -m timeit -r 10 -n 1000000 --setup 'from lxml import etree, objectify; root = objectify.XML("<root><x>1000_000.123</x><y>1000_000</y><z>1000_000_</z></root>")' "$EXPR"); echo; done; done;) === root.x 4.6.2 1000000 loops, best of 10: 2.69 usec per loop 4.6.3 1000000 loops, best of 10: 2.53 usec per loop === root.y 4.6.2 1000000 loops, best of 10: 1.26 usec per loop 4.6.3 1000000 loops, best of 10: 2.57 usec per loop === root.z 4.6.2 1000000 loops, best of 10: 3.08 usec per loop 4.6.3 1000000 loops, best of 10: 2.54 usec per loop Holger Landesbank Baden-Wuerttemberg Anstalt des oeffentlichen Rechts Hauptsitze: Stuttgart, Karlsruhe, Mannheim, Mainz HRA 12704 Amtsgericht Stuttgart HRA 4356, HRA 104 440 Amtsgericht Mannheim HRA 40687 Amtsgericht Mainz Die LBBW verarbeitet gemaess Erfordernissen der DSGVO Ihre personenbezogenen Daten. Informationen finden Sie unter https://www.lbbw.de/datenschutz.

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Re: lxml.objectify interprets <x>1000_000</x> as int in Python>3.6 - should it?
by Holger.Joukl＠LBBW.de 14 Sep '21

14 Sep '21

> > Then we shouldn't make it one. It's unlikely that data gets passed > > through XML in Python syntax. We have the same for "True" and "False", > > which come out as str, not bool. And this applies to FloatElement as > > well, which uses > > float() as parser and thus also supports "_" in Py3.6+. > > > > I'll see what I can come up with. > > https://github.com/lxml/lxml/commit/83e6c031994d553b74991501c6cd85e3517fadd > 8 Works great! Nice touch with the fuzzy tester ;-). Some super-simple "benchmarking" indicates there's no noticeable slowdown: # we're on 4.6.2 so far, haven't bothered to update to latest 4.6.3 release 0 $ (PYTHONPATH=$PYTAF_HOME/2020-Q3-V2/lib/python3.6/site-packages/ python3 -c 'from lxml import etree, objectify; print(etree.__version__); root = objectify.XML("<root><x>1000000</x><y>1000_000</y></root>"); print(objectify.dump(root))') 4.6.2 root = None [ObjectifiedElement] x = 1000000 [IntElement] y = 1000000 [IntElement] 0 $ (PYTHONPATH=$PYTAF_HOME/2020-Q3-V2/lib/python3.6/site-packages/ python3 -m timeit -r 5 -n 1000000 --setup 'from lxml import etree, objectify' 'root = objectify.XML("<root><x>1000000</x><y>1000_000</y></root>")') 1000000 loops, best of 5: 17.5 usec per loop # current gh version (version number still 4.6.3, from latest release) 0 $ (PYTHONPATH=build/lib.linux-x86_64-3.6/ python3 -c 'from lxml import etree, objectify; print(etree.__version__); root = objectify.XML("<root><x>1000000</x><y>1000_000</y></root>"); print(objectify.dump(root))') 4.6.3 root = None [ObjectifiedElement] x = 1000000 [IntElement] y = '1000_000' [StringElement] 0 $ (PYTHONPATH=build/lib.linux-x86_64-3.6/ python3 -m timeit -r 5 -n 1000000 --setup 'from lxml import etree, objectify' 'root = objectify.XML("<root><x>1000000</x><y>1000_000</y></root>")') 1000000 loops, best of 5: 17.1 usec per loop (No it's not faster, this is just a lucky timeit run - but it's absolutely in the same ballpark as before) Thanks a lot! Holger Landesbank Baden-Wuerttemberg Anstalt des oeffentlichen Rechts Hauptsitze: Stuttgart, Karlsruhe, Mannheim, Mainz HRA 12704 Amtsgericht Stuttgart HRA 4356, HRA 104 440 Amtsgericht Mannheim HRA 40687 Amtsgericht Mainz Die LBBW verarbeitet gemaess Erfordernissen der DSGVO Ihre personenbezogenen Daten. Informationen finden Sie unter https://www.lbbw.de/datenschutz.

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[newbie] Why can't find elements? What's the difference between // and .//?
by Gilles 13 Sep '21

13 Sep '21

Hello, A couple more newbie questions: 1. Using findall or xpath, what's the difference between "//" and ".//"? I see both in examples. https://www.w3schools.com/xml/xpath_syntax.asp 2. Why does the following script fail finding the elements I wish to remove from the tree? ********************* SCRIPT import lxml.etree as et from lxml import html import sys #Exit if no input file on command line arguments = len(sys.argv) - 1 if arguments != 1: print ("Must pass one KML file") sys.exit() inputfile = sys.argv[1] parser = et.XMLParser(remove_blank_text=True) tree = et.parse(inputfile,parser) root = tree.getroot() #=========== Remove namespace prefixes #https://stackoverflow.com/questions/60486563/remove-namespace-from-xml-with-comment-python for elem in root.getiterator(): # For elements, replace qualified name with localname if not(type(elem) == et._Comment): elem.tag = et.QName(elem).localname # Remove attributes that are in a namespace for attr in elem.attrib: if "{" in attr: elem.attrib.pop(attr) # Remove unused namespace declarations et.cleanup_namespaces(root) #=========== Remove blocs/elements: snippet, LookAt, Style, StyleMap #https://stackoverflow.com/questions/22560862/elementtree-findall-or-operator tracks = root.findall('.//snipet|.//LookAt|.//Style|.//StyleMap') if len(tracks): print("Elements found: snippet, LookAt, Style, StyleMap") #remove elements else: print("No elements found: snippet, LookAt, Style, StyleMap") #print(et.dump(root)) Here's the input data: ********************* DATA <?xml version="1.0" encoding="UTF-8"?> <kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2"> <Document> <snippet>Created lun. août 30 21:02:41 2021</snippet> <LookAt> <longitude>1.151909</longitude> <latitude>44.789630</latitude> <range>322203.100706</range> </LookAt> <Style id="track_n"> <IconStyle> <scale>.5</scale> <Icon> <href>https://earth.google.com/images/kml-icons/track-directional/track-none.png</href> </Icon> </IconStyle> <LabelStyle> <scale>0</scale> </LabelStyle> </Style> <StyleMap id="track"> <Pair> <key>normal</key> <styleUrl>#track_n</styleUrl> </Pair> <Pair> <key>highlight</key> <styleUrl>#track_h</styleUrl> </Pair> </StyleMap> <Folder> <name>Tracks</name> <Folder> <name>Some track</name> <snippet/> <Placemark> <name>Path</name> <styleUrl>#lineStyle</styleUrl> <LineString> <coordinates> 0.156119,45.649872,101.25 0.156389,45.649822,100.25 </coordinates> </LineString> </Placemark> </Folder> </Folder> </Document> </kml> Thank you.

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lxml - The Python XML Toolkit September 2021