How to save an etree xml object? saving loading lxml etree objects issue

Question

I have a etree object called projectxml:

projetxml type <type 'lxml.etree._Element'>

I need to save it on disk, so I convert it to element tree:

savedxml=et.ElementTree(projetxml)
savedxml.write('/home/simon/Vysis.xml')

An other script had to load the the Vysis.xml and two other files of the same kind:

vysis=et.parse('/home/simon/Vysis.xml')
asi=et.parse('/home/simon/ASI.xml')
psi=et.parse('/home/simon/PSI.xml')

Now asi, psi and vysis lxml objects are of the type for example:

<lxml.etree._ElementTree object at 0xa7eaf8c>

My problem is that I can no more do:

R=et.Element('DataBase')
R.append(asi)
R.append(psi)
R.append(vysis)

because of the error:

R.append(asi)
  File "lxml.etree.pyx", line 697, in lxml.etree._Element.append (src/lxml  /lxml.etree.c:35471)
TypeError: Argument 'element' has incorrect type (expected lxml.etree._Element, got lxml.etree._ElementTree)

I suppose I have two solutions. The first one could be to avoid to convert etree.Element to etree.ElementTree and to save it "directly", but I don't know how. The second solution would be to back convert etree.ElementTree to etree.Element type...There should be a clean solution to save/load a xml object?

Answer 1

The parse function returns an ElementTree, not an Element. If you want to use the results of parse as elements, you need to call getroot.

vysis=et.parse('/home/simon/Vysis.xml').getroot()
asi=et.parse('/home/simon/ASI.xml').getroot()
psi=et.parse('/home/simon/PSI.xml').getroot()

R=et.Element('DataBase')
R.append(asi)
R.append(psi)
R.append(vysis)