[lxml] Having all namespace declarations in the root element

Feb. 12, 2015

      Hi,

I made an XML doc grabbing and assembling nodes from various stuffs.
namespace declarations are consistent but repeated among various descendant
elements. And I want to gather all these namespace declarations in the root
element.

i. e. when I have :

<root>
  <foo xmlns:abc="abc.namespace">
    <abc:bar attrib="value"> blah </abc:bar>
  </foo>
  <joe  xmlns:abc="abc.namespace">
    <abc:stuff> stuff </abc:stuff>
  </joe>
</root>

Then  I need (once serialized with .tostring(...) :

<root  xmlns:abc="abc.namespace">
  <foo>
    <abc:bar attrib="value"> blah </abc:bar>
  </foo>
  <joe>
    <abc:stuff> stuff </abc:stuff>
 </joe>
</root>

I naively thought that merging all elements .nsmap attribs into the
root.nsmap should do the job, but it appears that changes to the
Element.nsmap mapping fail silently.

My code (what I want to do with a really mutable .nsmap) :

----

etree.cleanup_namespaces(doc)

for elem in doc.getiterator():

    if hasattr(elem, 'nsmap'):

        for k in elem.nsmap:

            doc.nsmap[k] = elem.nsmap.pop(k)

----

Unfortunately .nsmap attrib is a so called "non mutable dict but ignoring
silently mutation attempts". Thus this code does not work as expected.

Any hint to unlock me is welcome.

Best regards

-- 

Gilles Lenfant