Re: xml-file as foreign table?

def q(v):
     return b'"' + v.replace(b'"', b'""') + b'"'

return b','.join(q(f) for f in fields) + b'\n'

In the end I also had some other problems with the XML (namespaces), so I used:

etree.tostring(element, method='c14n', exclusive=True)