Static python method to XML escape string which supports quotes

Question

I have a string that have both XML escaped characters and non-escaped, and I need it to be 100% XML valid, example:

>>> s = '< &lt;'

I want this to be:

>>> s = '< <'

I have tried numerous methods with, lxml, cgi etc.. but they all expect the input string to not have any valid XML characters already:

>>> import cgi
>>> cgi.escape("< &lt;")
'&lt; &amp;lt;'

or

>>> from xml.sax.saxutils import escape
>>> escape("< &lt;")
'&lt; &amp;lt;'

Isn't there a standard method for this already?

Someone has to have had the same problem :)

Answer 1

Your best bet is to unescape, then to re-escape:

>>> from xml.sax.saxutils import escape, unescape
>>> unescape("< &lt;")
'< <'
>>> escape(unescape("< &lt;"))
'&lt; &lt;'