pickling error in python?

Question

I am getting this error, and I dont know what it means. How can I fix this problem?

my code looks like this, I've used it before and it has worked:

parentdir = os.getcwd()
dirlist = os.listdir(parentdir)

for dir in dirlist:
    if not dir == "pubs_edits": continue
    if os.path.isdir(os.path.join(parentdir, dir)):
                        os.chdir(os.path.join(parentdir, dir))
                        file_list = os.listdir(os.path.join(parentdir, dir))
                        for f in file_list:
                            in1 = open(f, 'r')
                            dict2 = pickle.load(in1)

This is the error message:

    File "/home/md202/pmid_editor.py", line 18, in <module>
        dict2 = pickle.load(in1)
    File "/usr/lib/python2.5/pickle.py", line 1370, in load
        return Unpickler(file).load()
    File "/usr/lib/python2.5/pickle.py", line 858, in load
        dispatch[key](self)
KeyError: '\x00'

Answer 1

This exact error occurred for me when I tried to unpickle (using pickle.loads) a string representation that I had stored in a database via django. Django changed the charactee representation of my string so that pickle.loads(mystring) threw me that error. When I added an explicit string conversion in, it was fine: pickle.loads( str(mystring) )

EDIT: looking at the comments on the original post, I think this is related to the unicode string issue mentioned. I put a normal string into the database, and django gives me back a unicode string that produces this error.