Mailman 3 March 2007 - lxml - The Python XML Toolkit

[lxml-dev] Pickling objectified trees
by Christian Zagrodnick June 9, 2008

June 9, 2008

Hi, the other day I had to pickle objectified trees. I just thought to share my findings. Pickling is about serialization. IMHO the natural serialization of an objectified tree is its XML representation. So the following basically does that: -------------------------- import copy_reg import lxml.etree import lxml.objectify def treeFactory(state): """Un-Pickle factory.""" return lxml.objectify.fromstring(state) copy_reg.constructor(treeFactory) def reduceObjectifiedElement(object): """Reduce function for lxml.objectify trees. See http://docs.python.org/lib/pickle-protocol.html for details. """ return (treeFactory, (lxml.etree.tostring(object), )) copy_reg.pickle(lxml.objectify.ObjectifiedElement, reduceObjectifiedElement, treeFactory) ----------------------------------------- You might consider just registering the reduce function in lxml itself. Shouldn't hurt, should it. -- Christian Zagrodnick gocept gmbh & co. kg · forsterstrasse 29 · 06112 halle/saale www.gocept.com · fon. +49 345 12298894 · fax. +49 345 12298891

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[lxml-dev] lxml namespaces
by Maxim Sloyko Feb. 20, 2008

Feb. 20, 2008

Hi All! I have a little problem with XML namespaces. In my application I have two XML processors, that process the same document, one after the other. The first one looks for nodes in 'ns1' namespace, and substitutes them, according to some algorithm. After this processor is finished, it is guaranteed that there are no more 'ns1' nodes left in the tree. 'ns1' namespace dclaration is still there, in the root node (well, I put it there manually). Now, when this namespace is no longer needed, I want to get rid of it, because it confuses some other processors (namely, my browser) So, the question is, how do I do that? del tree.getroot().nsmap['ns1'] does not seem to do the trick :( Thanks in advance and Happy Holidays! -- Maxim Sloyko

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[lxml-dev] Parsing Information
by Stephan Richter April 15, 2007

April 15, 2007

Hi all, I have recently reimplemented RML (Reportlab's XML format to generate PDFs) using lxml. All works well. Now, I would like to give my users some more information when an error occurs. For a pure XML parsing error, everything is fine (though I found the failure points hard to interpret at times). But what if the XML parses correctly, but while working with the element tree an error occurs? In this case I would like to tell the user not only the error message, but also the line/column and filename of point of failure. Ideally I would have the filename, start row and start column of each element available as part of the etree Element. I have tried to find this information or hooks for it.unsuccessfully. Could someone help me out here? Regards, Stephan -- Stephan Richter CBU Physics & Chemistry (B.S.) / Tufts Physics (Ph.D. student) Web2k - Web Software Design, Development and Training

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Re: [lxml-dev] newb: How to create a simple xml file?
by Stefan Behnel March 30, 2007

March 30, 2007

Ram Peters wrote: > I needed to know how to create xml headers, using lxml like this: > <?xml version="1.0" encoding="UTF-8"?> ? Hmm, why? By specification, there is no difference between this <?xml version="1.0" encoding="UTF-8"?> <weatherNow xmlns="http://example.com/weatherNow/"> <temperature>57</temperature> <pressure>29.97</pressure> <pressureChange>rising</pressureChange> </weatherNow> and this <weatherNow xmlns="http://example.com/weatherNow/"> <temperature>57</temperature> <pressure>29.97</pressure> <pressureChange>rising</pressureChange> </weatherNow> However, if you really need to output the header, pass the "xml_declaration=True" keyword argument to tostring() or write(). Hope it helps, Stefan > On 29/03/07, Stefan Behnel <stefan_ml(a)behnel.de> wrote: >> >> > How to create a simple xml file like the one below in lxml? >> > >> > <?xml version="1.0" encoding="UTF-8"?> >> > <weatherNow xmlns="http://example.com/weatherNow/"> >> > <temperature>57</temperature> >> > <pressure>29.97</pressure> >> > <pressureChange>rising</pressureChange> >> > </weatherNow> >> >> Hi, >> >> what about reading some of the documentation? >> >> http://codespeak.net/lxml/#documentation >> >> Given your target XML above (which is data style, not document style >> XML), you >> might especially be interested in the objectify API. >> >> http://codespeak.net/lxml/objectify.html >> http://codespeak.net/lxml/objectify.html#creating-objectify-trees >> >> Hope it helps, >> Stefan >>

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[lxml-dev] Expose _assertHasRoot as part of the API?
by Sidnei da Silva March 29, 2007

March 29, 2007

Hi, I'm facing an issue here, that if applying a XSLT the resulting document is empty, the only way to check that is to call _assertHasRoot and catch the AssertionError apparently. Obviously catching AssertionError's is not very recommended, specially because they tend to not be raised when running with -O. Can we add a public API to check if a element tree is empty? Maybe isEmpty()? -- Sidnei da Silva Enfold Systems http://enfoldsystems.com Fax +1 832 201 8856 Office +1 713 942 2377 Ext 214

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[lxml-dev] Problem with lxml-1.1.2 and binary text nodes
by Narayan Desai March 29, 2007

March 29, 2007

I seem to recall that Lxml used to raise an exception if binary data was put into a text node of an xml element. Was this change intentional? Is there any way to use lxml to check for document well-formedness before sending out xml? thanks... -nld

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Re: [lxml-dev] newb: How to create a simple xml file?
by Stefan Behnel March 29, 2007

March 29, 2007

Ram Peters wrote: > How to create a simple xml file like the one below in lxml? > > <?xml version="1.0" encoding="UTF-8"?> > <weatherNow xmlns="http://example.com/weatherNow/"> > <temperature>57</temperature> > <pressure>29.97</pressure> > <pressureChange>rising</pressureChange> > </weatherNow> Hi, what about reading some of the documentation? http://codespeak.net/lxml/#documentation Given your target XML above (which is data style, not document style XML), you might especially be interested in the objectify API. http://codespeak.net/lxml/objectify.html http://codespeak.net/lxml/objectify.html#creating-objectify-trees Hope it helps, Stefan

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[lxml-dev] newb: How to create a simple xml file?
by Ram Peters March 29, 2007

March 29, 2007

How to create a simple xml file like the one below in lxml? <?xml version="1.0" encoding="UTF-8"?> <weatherNow xmlns="http://example.com/weatherNow/"> <temperature>57</temperature> <pressure>29.97</pressure> <pressureChange>rising</pressureChange> </weatherNow> Thank you.

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Re: [lxml-dev] A bit of oddness in the HTML parser
by Stefan Behnel March 27, 2007

March 27, 2007

Jim Washington wrote: >>>> s = '<div>d_txt<script src="blah">s_tail</div>' > > and I use the HTML parser on that string, I get the ending div > html-escaped in the script's text. > >>>> r = HTML(s) >>>> tostring(r) > '<html><body><div>d_txt<script > src="blah">s_tail</div></script></div></body></html>' > > I'm guessing this is upstream behavior? Definitely. There is always an end to what a machine can fix in tag soup. Feel free to file a request for enhancement on libxml2's HTML parser. Stefan

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[lxml-dev] A bit of oddness in the HTML parser
by Jim Washington March 27, 2007

March 27, 2007

I'm seeing that the HTML parser is doing something undesirable. If I have (note, the script tag is not closed): >>> s = '<div>d_txt<script src="blah">s_tail</div>' and I use the HTML parser on that string, I get the ending div html-escaped in the script's text. >>> r = HTML(s) >>> tostring(r) '<html><body><div>d_txt<script src="blah">s_tail</div></script></div></body></html>' I'm guessing this is upstream behavior? I was hoping to get '<html><body><div>d_txt<script src="blah">s_tail</script></div></body></html>' I think I can live with this behavior if nobody else thinks this is a bug. Yes, I realize that tag-soup parsers are hard to do. :) -Jim Washington

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