2015-02-12 15:07 GMT+01:00 Charlie Clark :

Am .02.2015, 14:59 Uhr, schrieb Gilles Lenfant :

Hi,

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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"> blah </foo> <joe xmlns:abc="abc.namespace"> abc:stuff stuff </joe> </root> Then I need (once serialized with .tostring(...) : <root xmlns:abc="abc.namespace"> <foo> blah </foo> <joe> abc:stuff stuff </joe> </root>

I naively thought that merging all elements .nsmap attribs into the

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root.nsmap should do the job, but it appears that changes to the Element.nsmap mapping fail silently.

I think this happens to us all at some point. What you need to do is use the nsmap argument when creating your root element and pass it in a dictionary of (prefix, namespace).

Charlie -- Charlie Clark Managing Director Clark Consulting & Research German Office Kronenstr. 27a Düsseldorf D- 40217 Tel: +49-211-600-3657 Mobile: +49-178-782-6226 _________________________________________________________________

Many thanks Charlie for that fast and efficient hint, For those who will search for the solution in the ML archive, here it is : -------- etree.cleanup_namespaces(doc) global_nsmap = {} for elem in doc.getiterator(): if hasattr(elem, 'nsmap'): global_nsmap.update(elem.nsmap) new_doc = etree.Element(doc.tag, nsmap=global_nsmap) for elem in doc: new_doc.append(elem) etree.cleanup_namespaces(new_doc) --------

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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"> blah </foo> <joe xmlns:abc="abc.namespace"> abc:stuff stuff </joe> </root> Then I need (once serialized with .tostring(...) : <root xmlns:abc="abc.namespace"> <foo> blah </foo> <joe> abc:stuff stuff </joe> </root>

[...] Would it help if the ElementMaker (a.k.a. E-factory) aggregated the namespace declarations of the children it receives? I don't think this is worth changing the way Elements work overall, but changing the ElementMaker sounds doable and reasonable to me.

Did the OP actually use the E-factory for tree assembly? Or you probably mean one should then use it to combine nodes to assemble, if aggregation is desired. Maybe a convenience helper like cleanup_namespaces(...) could be useful? Or a switch to make cleanup_namespaces optionally propagate namespace declarations "upwards" in the tree, if possible (i.e. there's no remapping of the prefix). Holger Landesbank Baden-Wuerttemberg Anstalt des oeffentlichen Rechts Hauptsitze: Stuttgart, Karlsruhe, Mannheim, Mainz HRA 12704 Amtsgericht Stuttgart

Stefan Behnel schrieb am 13.02.2015 um 10:58:

Holger Joukl schrieb am 13.02.2015 um 10:38:

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Would it help if the ElementMaker (a.k.a. E-factory) aggregated the namespace declarations of the children it receives? I don't think this is worth changing the way Elements work overall, but changing the ElementMaker sounds doable and reasonable to me.

Did the OP actually use the E-factory for tree assembly? Or you probably mean one should then use it to combine nodes to assemble, if aggregation is desired.

Yes. Although I guess that most data would already be passed through cleanup_namespaces() anyway when this comes up as an issue, so that might be the 'cleaner' canonical solution.

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Maybe a convenience helper like cleanup_namespaces(...) could be useful? Or a switch to make cleanup_namespaces optionally propagate namespace declarations "upwards" in the tree, if possible (i.e. there's no remapping of the prefix).

The latter, I think, maybe as an explicit nsmap that declares the namespaces on the Element that was passed in, iff they are used in the tree.

Have fun: https://github.com/lxml/lxml/commit/4a1c2e9ff3c99247ec1da2707b29e3bb336d641d Stefan