lxml - The Python XML Toolkit June 2019

lxml@python.org

2 participants
7 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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Accessing variables from within an XSL file
by Adrian Bool 05 Apr '21

05 Apr '21

Hi, I'm trying to extract from data from XSL files on an IBM DataPower system. I can't change the XSLT files - and therefore need to work around their current structure to get the info I need. I'm doing this from within Python 3.7 using etree.__version__ 4.3.3. Here are my imports, a dummy XML object and a cutdown version of the XSL file from the IBM system: from lxml import etree from textwrap import dedent xml = etree.XML("""<root></root>""") xsl = etree.XML(dedent( """<?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:dp="http://www.datapower.com/extensions" extension-element-prefixes="dp"> <xsl:template match="node()|@*"> <xsl:copy> <xsl:apply-templates select="node()|@*"/> </xsl:copy> <xsl:variable name="destination_url"> <xsl:value-of select="'https://my.domain.example.com/'" /> </xsl:variable>  <dp:set-variable name="'var://context/mpgw/Destination'" value="$destination_url" /> </xsl:template> </xsl:stylesheet> """)) My goal is to use lxml to process this file and extract the contents of the DataPower variable 'var://context/mpgw/Destination' - i.e. the contents of the xsl:variable $destination_url - in the above case ' https://my.domain.example.com/'. I've created an XSLT extension for the "dp:set-variable" element to try to capture this information: class MyExtElement(etree.XSLTExtension): def execute(self, context, self_node, input_node, output_parent): if self_node.tag == '{ http://www.datapower.com/extensions}set-variable': print(f"Setting variable of name {self_node.get('name')} to value {self_node.get('value')}") extensions = { ('http://www.datapower.com/extensions', 'set-variable') : MyExtElement() } result = etree.XSLT(xsl, extensions=extensions)(xml) print(f"Result: {result}") When this is being called; instead of the value of destination_url I'm getting the static "$destination_url" string instead - with the output of the above script being: Setting variable of name 'var://context/mpgw/Destination' to value $destination_url Result: <?xml version="1.0"?> <root/> I am rather suprised that the $destination_url xsl:variable was not being evaluated - does anyone know why this is the case? Given the above, I've been trying to find a way to access the $destination_url xsl:variable from within my XSLTExtension - but unfortunately with no luck. Some things I've tried: * Calling self.process_children(context) within the extension - this just results in an empty list. * I've used dir() to look through the context, self_node and input_node args to try to find somewhere the variables may be accessible but with no luck. * I've used deepcopy to clone self_node to get an xpath function on this argument and made some attempts at using xpath to access the xsl variable - all unsuccessful: node = deepcopy(self_node) node.xpath("""<xsl:value-of select="$destination_url">""") *** lxml.etree.XPathEvalError: Invalid expression node.xpath("""$destination_url""") *** lxml.etree.XPathEvalError: Undefined variable node.xpath("""xsl:$destination_url""") *** lxml.etree.XPathEvalError: Invalid expression node.xpath("""xsl:$destination_url""", namespaces={'xsl':'http://www.w3.org/1999/XSL/Transform'}) *** lxml.etree.XPathEvalError: Invalid expressio node.xpath("""$destination_url""", namespaces={'xsl':'http://www.w3.org/1999/XSL/Transform'}) *** lxml.etree.XPathEvalError: Undefined variable node.xpath("""/xsl:$destination_url""", namespaces={'xsl':'http://www.w3.org/1999/XSL/Transform'}) *** lxml.etree.XPathEvalError: Invalid expression node.xpath("""<xsl:value-of select="$destination_url">""", namespaces={'xsl':'http://www.w3.org/1999/XSL/Transform'}) *** lxml.etree.XPathEvalError: Invalid expression I'm lost now! Any suggestions greatly appreciated! Cheers, aid

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externalDTDs are overwritten when distinct multiply specified
by Ewan Willis 26 Jun '19

26 Jun '19

Hello lxml-ers! I have an existing DTD document that includes several external DTDs. Each of these external DTD will resolve( populating 'docinfo.internalDTD' ) if they are specified one at a time i.e. only one external DTD at a time in the DTD. However if two or more external DTDs are specified then only the entities from the first are loaded into the internalDTD. Am I doing it wrong or is this a bug? For an example, see the python program below. Note that I have local copies of xhtml-lat1.ent and xhtml-symbol.ent, which can be downloaded from http://www.w3.org/TR/xhtml1/DTD/xhtml-lat1.ent and http://www.w3.org/TR/xhtml1/DTD/xhtml-symbol.ent respectively # EXAMPLE START from lxml import etree from io import BytesIO parser = etree.XMLParser(load_dtd=True) xml = b'''\ <?xml version='1.1' encoding='utf-8' ?> <!DOCTYPE root [ <!ENTITY % HTMLlat1 PUBLIC "-//W3C//ENTITIES Latin 1 for XHTML//EN" "xhtml-lat1.ent"> %HTMLlat1; <!ENTITY % HTMLsymbol PUBLIC "-//W3C//ENTITIES Symbols for XHTML//EN" "xhtml-symbol.ent"> %HTMLsymbol; ]> <root></root>''' tree = etree.parse(BytesIO(xml), parser) print(tree.docinfo.internalDTD.entities()) # EXAMPLE END In the output I see all the entities that would be expected from xhtml-lat1.ent but xhtml-symbol.ent resolves to "<lxml.etree._DTDEntityDecl object name='HTMLsymbol' at 0x7fdbfc1c9b90>" and does not to the contain Entities such as "Alpha" which are present in the file. This behaviour is present in my python3 and python2 environments: $ pip freeze | grep lxml lxml==4.1.1 $ python2 --version Python 2.7.15 $ python --version Python 3.6.5 Note: I am able to work around this issue by combining the local DTD files into a single file

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a question about getpath()
by Martin Mueller 06 Jun '19

06 Jun '19

I assumed from the documentation that tree.getpath(someElement) would produce the XPath for that element, as in the example tree = etree.ElementTree(c) >>> print(tree.getpath(d2)) But if I do something analogous, as in for w in tree.iter(tei + 'w'): counter += 1 if counter < 10: print(tree.getpath(w)) else: break I get this output: /*/*[2]/*[1]/*[1]/*[3]/*[1]/* /*/*[2]/*[1]/*[1]/*[3]/*[2]/*[1] /*/*[2]/*[1]/*[1]/*[3]/*[2]/*[2] /*/*[2]/*[1]/*[1]/*[3]/*[2]/*[3] /*/*[2]/*[1]/*[1]/*[3]/*[2]/*[4] /*/*[2]/*[1]/*[1]/*[3]/*[2]/*[6] /*/*[2]/*[1]/*[1]/*[3]/*[2]/*[7] /*/*[2]/*[1]/*[1]/*[3]/*[2]/*[8] /*/*[2]/*[1]/*[1]/*[3]/*[2]/*[9] This does look like a sequence of XPaths, but without the element names. What am I not doing right?

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lxml - The Python XML Toolkit June 2019