Cannot load pickled object

Question

The problem I am having is when I try to load the pickled object. I have tried using both pickle.loads and pickle.load Here are the results:

pickle.loads:

TypeError: 'str' does not support the buffer interface

pickle.load:

TypeError: file must have 'read' and 'readline' attributes

Can someone please tell me what I am doing wrong in this process?

elif str(parser) == "SwissWithdrawn_Parser":     # swissprot name changes     print("Gathering SwissProt update info...")     cache_hits = 0     cache_misses = 0     files = set()      for f in os.listdir("out/cache/"):         if os.path.isfile("out/cache/" + f):             files.add(f)      for name in sp_lost_names:          cached = False         url = (             "http://www.uniprot.org/uniprot/?query=mnemonic%3a"             + name             + "+active%3ayes&format=tab&columns=entry%20name"         )         hashed_url = str(hash(url))          ################### For Testing Only - use cache ##################         if hashed_url in files:             cached = True             cache_hits += 1             content = pickle.loads("out/cache/" + hashed_url)  # <-- problematic line         else:             cache_misses += 1             content = urllib.request.urlopen(url)          # get the contents returned from the HTTPResponse object         content_list = [x.decode().strip() for x in content.readlines()]         if not cached:             with open("out/cache/" + hashed_url, "wb") as fp:                 pickle.dump(content_list, fp)         ####################################################################          # no replacement         if len(content_list) is 0:             change_log["swiss-names"] = {name: "withdrawn"}         # get the new name         else:             new_name = content_list[1]             change_log["swiss-names"] = {name: new_name} 

Answer 1

You need to either read the file first (as binary bytes) and use pickle.loads(), or pass an open file object to the pickle.load() command. The latter is preferable:

with open('out/cache/' +hashed_url, 'rb') as pickle_file:     content = pickle.load(pickle_file) 

Neither method supports loading a pickle from a filename.

Answer 2

If you happen to be porting python2 to 3 and run into this error, python2 and 3 handle bytes different leading to the requirement to open your file handle with the 'b' option. For instance in python2 open(file, 'r') as f: my_list = pickle.load(f) works , but not in python3. Instead you must open with open(file, 'rb') as f: my_list = pickle.load(f)