lxml - The Python XML Toolkit October 2016

lxml@python.org

5 participants
12 discussions

[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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htmlfile doesn't escape attribute values
by Burak Arslan 27 Dec '16

27 Dec '16

Hello, This is a heads-up for bug 1594155 here: https://bugs.launchpad.net/lxml/+bug/1594155 Please consider the following test case. >>> from lxml import html >>> from lxml.etree import htmlfile >>> from lxml.html.builder import E >>> from StringIO import StringIO >>> out = StringIO() >>> with htmlfile(out) as f: ... with f.element("tagname", attrib={"attr": '"misquoted"'}): ... f.write("foo") ... >>> out.getvalue() '<tagname attr=""misquoted"">foo</tagname>' Expected output: '<tagname attr=""misquoted"">foo</tagname>' Lack of proper escaping confuses the hell out of browsers :) Proper escaping is needed to safely put html documents inside srcdoc attribute of an <iframe>. The workaround is to quote the data before putting it inside an attribute. Fortunately, only replacing " with " is enough and & is also not escaped (but it should be). versions: Python : sys.version_info(major=2, minor=7, micro=11, releaselevel='final', serial=0) lxml.etree : (3, 6, 0, 0) libxml used : (2, 9, 3) libxml compiled : (2, 9, 3) libxslt used : (1, 1, 28) libxslt compiled : (1, 1, 28) Best regards, Burak

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XML schema validation error using 3.6.3
by Tom Kralidis 05 Nov '16

05 Nov '16

Hi all: moving from 3.6.2 to 3.6.3 introduces an XML Schema validation error. Test case: XML document: https://github.com/geopython/pycsw/blob/master/tests/suites/default/post/Ge… Associated XML Schema: http://schemas.opengis.net/csw/2.0.2/CSW-discovery.xsd (note there are numerous includes/imports. Full schema tree can be downloaded from http://schemas.opengis.net/SCHEMAS_OPENGIS_NET.zip). Code snippet: schema = etree.XMLSchema(file='/path/to/csw/2.0.2/CSW-discovery.xsd') parser = etree.XMLParser(schema=schema, resolve_entities=False) doc = etree.fromstring(postdata, parser) Result: Element '{http://www.opengis.net/cat/csw/2.0.2}GetRecordById', attribute 'service': The value '(null)' does not match the fixed value constraint 'CSW'. Testing results summary [1]: - lxml 3.6.1 && libxml2 2.9.1 passes - lxml 3.6.2 && libxml2 2.9.1 passes - lxml 3.6.3 && libxml2 2.9.4 FAILS with said validation error - lxml 3.6.4 && libxml2 2.9.4 FAILS with said validation error Any ideas? Is this a libxml2 issue? I notice 3.6.2 uses libxml2 2.9.1 whereas 3.6.3 uses libxml2 2.9.4 (on travis, fwiw). Let me know if you need more info or a clearer test case, or if/where I should file an issue. Thanks ..Tom [1] https://github.com/geopython/pycsw/pull/453

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Re: [lxml] attrname - get value of attrname
by Sayth Renshaw 10 Oct '16

10 Oct '16

> > > Date: Tue, 4 Oct 2016 > Subject: Re: [lxml] attrname - get value of attrname > Message-ID: > <OFB7C4D3DA.6DB2EE2B-ONC1258042.0021FC9D-C1258042.0023169A(a)LBBW.de > > > Content-Type: text/plain; > The result of tree.xpath('//meeting/@*') is already a list of attribute > *values*. > These are "smart strings" i.e. strings with additional niceties (like > the .attrname > attribute, see http://lxml.de/xpathxslt.html#xpath) and should just work > in > your usual > string contexts. > > E.g. > > >>> root = etree.fromstring("""<root><x a="a attr"/><y b="b attr"/> > </root>""") > >>> root.xpath('//@*') > ['a attr', 'b attr'] > >>> root.xpath('//@*')[0] > 'a attr' > >>> root.xpath('//@*')[0].attrname > 'a' > >>> root.xpath('//@*')[1] + " is nice to have" > 'b attr is nice to have' > > If need be you can always convert them to plain strings using unicode() or > str(), > > > > > Thank you i definitely got a working version. I can't help thinking though > i have not optimally used lxml. A key thing is, well 2; other than with my eyes what is a good way with lxml to check that the values i am obtainjng are correct especially when as i am going over multiple files. Should I be randomly generating a file in reverse and comparing to the original? Second the xml is only 4 levels deep with 5 main nodes comprising these levels. However each node is attribute heavy (10+). While i have used getchildren etc to reduce looping down i still have looped down to the main extent. Each line of my csv output contains details from each node. So abstracted thats my flow start at root grab a few and at each level repeat and then create a line for csv written later. How do you approach these tasks? Thanks Sayth

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Issue with objectify.parse / lxml.etree.XMLSyntaxError
by Thomas Burg 10 Oct '16

10 Oct '16

Hello I am facing an issue using objecjtify.parse when I provide a parser. The function rise lxml.etree.XMLSyntaxError, but I don't understand why. My file validate : >xmllint --noout --schema XMLSchema.xsd myxsd.xsd myxsd.xsd validates from __future__ import print_function from lxml import etree from lxml import objectify print("libxml_version:"+str(etree.LIBXML_VERSION)) print("libxslt_version:"+str(etree.LIBXSLT_VERSION)) print("lxml_version:"+str(etree.LXML_VERSION)) rawXMLSchema = etree.parse('XMLSchema.xsd') XMLSchema = etree.XMLSchema(rawXMLSchema) doc = etree.parse("myxsd.xsd") valid = XMLSchema.validate(doc) print ('valid: {var}'.format(var=valid)) XMLSchemaParser = objectify.makeparser(schema = XMLSchema) root = objectify.parse('myxsd.xsd',parser=XMLSchemaParser) print("done") Also the exception message is different according to lxml version: libxml_version:(2, 9, 3) libxslt_version:(1, 1, 28) lxml_version:(3, 5, 0, 0) lxml.etree.XMLSyntaxError: Element '{http://www.w3.org/2001/XMLSchema}attribute', attribute 'ref': The QName value 'xml:id' has no corresponding namespace declaration in scope. After pip install --user -U lxml libxml_version:(2, 9, 4) libxslt_version:(1, 1, 29) lxml_version:(3, 6, 4, 0) lxml.etree.XMLSyntaxError: Element '{http://www.w3.org/2001/XMLSchema}simpleType', attribute 'name': '' is not a valid value of the atomic type 'xs:NCName'. How lxml can report libxml_version:(2, 9, 4) while I can only find libxml2.so.2.9.3 on my system ? I am on Ubuntu 16.04.1 Is the issue coming from my file or from the tool ? I see a previous post on this mailing list where libxml2 version 2.9.4 was the one to blame. But in current case I try with 2 different versions and my knowledge of xml, lxml and libxml2 can't help me to conclude. Any help would be welcome. Thomas

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an odd result with addprevious
by Martin Mueller 10 Oct '16

10 Oct '16

I see my mistake: I assumed that the text string was part of the <l> element, but it’s the “tail” of the pb element, and the l element appears very properly as an empty element. This is a part of lxml that I need to wrap my head around I am trying to mov e <pb/> elements in a TEI document from a position at the top of a block to a position between the block elements. So I thought up a toy problem, using the following text: <root> <l>Mary had a little lamb, little lamb,</l> <l><pb/>little lamb, Mary had a little lamb</l> <l>whose fleece was white as snow.</l> <l>And everywhere that Mary went</l> <l>Mary went, Mary went, everywhere</l> <l>that Mary went</l> <l> The lamb was sure to go.</l> </root> I used the following code: from lxml import etree Mary = '/users/martin/dropbox/allerlei/Mary.xml' tree = etree.parse(Mary) for pb in tree.iter('pb'): parent = pb.getparent() print(parent.tag) parent.addprevious(pb) print(etree.tostring(tree, encoding='unicode')) This produces the following output: l <root> <l>Mary had a little lamb, little lamb,</l> <pb/>little lamb, Mary had a little lamb<l/> <l>whose fleece was white as snow.</l> <l>And everywhere that Mary went</l> <l>Mary went, Mary went, everywhere</l> <l>that Mary went</l> <l> The lamb was sure to go.</l> </root> The output does most of the things right and moves the pb element from child of l to child of root. But the output doesn’t show the opening tag for the l element, so that the document is not a well-formed document. Oddly enough, this code works as intended in a TEI text were all text is wrapped in <w> elements. Since that is the kind of text I’m working with, I’m happy enough. But I am curious about the dropping of the opening tag of the l element. Is that a bug, am I doing something wrong, or do I just not know enough about “mixed XML”.

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an odd result with addprevious
by Martin Mueller 10 Oct '16

10 Oct '16

I am trying to mov e <pb/> elements in a TEI document from a position at the top of a block to a position between the block elements. So I thought up a toy problem, using the following text: <root> <l>Mary had a little lamb, little lamb,</l> <l><pb/>little lamb, Mary had a little lamb</l> <l>whose fleece was white as snow.</l> <l>And everywhere that Mary went</l> <l>Mary went, Mary went, everywhere</l> <l>that Mary went</l> <l> The lamb was sure to go.</l> </root> I used the following code: from lxml import etree Mary = '/users/martin/dropbox/allerlei/Mary.xml' tree = etree.parse(Mary) for pb in tree.iter('pb'): parent = pb.getparent() print(parent.tag) parent.addprevious(pb) print(etree.tostring(tree, encoding='unicode')) This produces the following output: l <root> <l>Mary had a little lamb, little lamb,</l> <pb/>little lamb, Mary had a little lamb<l/> <l>whose fleece was white as snow.</l> <l>And everywhere that Mary went</l> <l>Mary went, Mary went, everywhere</l> <l>that Mary went</l> <l> The lamb was sure to go.</l> </root> The output does most of the things right and moves the pb element from child of l to child of root. But the output doesn’t show the opening tag for the l element, so that the document is not a well-formed document. Oddly enough, this code works as intended in a TEI text were all text is wrapped in <w> elements. Since that is the kind of text I’m working with, I’m happy enough. But I am curious about the dropping of the opening tag of the l element. Is that a bug, am I doing something wrong, or do I just not know enough about “mixed XML”.

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lxml - The Python XML Toolkit October 2016