Python pickle to xml

Question

How can I convert to a pickle object to a xml document?

For example, I have a pickle like that:

cpyplusplus_test
Coordinate
p0
(I23
I-11
tp1
Rp2
. 

I want to get something like:

<Coordinate>
  <x>23</x>
  <y>-11</y>
</Coordinate>

The Coordinate class has x and y attributes of course. I can supply a xml schema for conversion.

I tried gnosis.xml module. It can objectify xml documents to python object. But it cannot serialize objects to xml documents like above.

Any suggestion?

Thanks.

Answer 1

gnosis.xml does support pickling to XML:

import gnosis.xml.pickle
xml_str = gnosis.xml.pickle.dumps(obj)

To deserialize the XML, use loads:

o2 = gnosis.xml.pickle.loads(xml_str)

Of course, this will not directly convert existing pickles to XML — you have to first deserialize them into live object, and then dump them to XML.

Having said that, I must warn you that gnosis.xml is quite slow, somewhat fragile, and most likely unmaintained (last release was over six years ago). It is also very bloated, containing a huge number of subpackages with lots and lots of features that not only you won't need, but are untested and buggy. We tried to use for our development and, after a lot of effort wasted on trying to debug and improve it, ended up writing a simple XML pickler running at ~500 lines of code, and never looked back.

Answer 2

First you need to unpickle the data by pickle.load or pickle.loads. Then generate xml snippet. If you have a pickle in tmpStr variable, simply do this:

c = pickle.loads(tmpStr)
print '<Coordinate>\n<x>%d</x>\n<y>%d</y>\n</Coordinate>' % (c.x, c.y)

Writing to file is left as an exercise to the reader.