[lxml-dev] lxml.objectify.deannotate refuses to clean nil nodes

[jholg at gmx.de]

Hi,

> The nil node <Fubar/> is not deannotated as I would expect in the
> following
> snippet.  I could not find a reference to this behaviour in the archives
> or
> documentation.  Is this a design feature for which there is a work around,
> or a bug?  I'm using lxml-2.2-py2.5-linux-i686.

Design feature. Only py:pytype/xsi:type attributes get removed by deannotate():

>>> print etree.__version__
2.1.5
>>> help(objectify.deannotate)

Help on built-in function deannotate in module lxml.objectify:
 
deannotate(...)
    deannotate(element_or_tree, pytype=True, xsi=True)
 
    Recursively de-annotate the elements of an XML tree by removing 'pytype'
    and/or 'type' attributes.
 
    If the 'pytype' keyword argument is True (the default), 'pytype' attributes
    will be removed. If the 'xsi' keyword argument is True (the default),
    'xsi:type' attributes will be removed.

IMHO the xsi:nil concept in XML Schema pretty much corresponds to NULL values in databases, i.e. a typed element/column may (or may not) be xsi:nil/NULL, but it does not so directly translate to the distinct Python None object. OTOH I think mapping xsi:nil to None very much captures the meaning of xsi:nil/NULL, because in most use cases you'd test if a value has been set (!=None) or not (==None).

Or course, you can always easily get rid of xsi:nil if you wish so:

>>> for elt in root.iter(): elt.attrib.pop('{http://www.w3.org/2001/XMLSchema-instance}nil', None)

Holger
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