I'm trying to unpickle an object stored as a blob in a MySQL database. I've manually generated and stored the pickled object in the database, but when I try to unpickle the object, I get the following rather cryptic exception:
ImportError: No module named copy_reg
Any ideas as to why this happens?
Method of Reproduction
Note: Must do step 1 on a Windows PC and steps 3 and 4 on a Linux PC.
1) On a Windows PC:
file = open("test.txt", "w") thing = {'a': 1, 'b':2} cPickle.dump(thing, file)
2) Manually insert contents of text.txt into blob field of MySQL database running on linux
3) In Python running on a linux machine, fetch the contents of column from MySQL
4) Assuming that you put the contents of the blob column into a variable called data, try this:
cPickle.loads(rawString)
It seems this might be caused by my method of exporting the pickled object.
This bug report seens to suggest that my issue can be resolved by exporting to a file writen in binary mode. I'm going to give this a go now and see if this solves my issue.
UPDATE: This works. The solution is to make sure you export your pickled object to a file open in binary mode, even if you are using the default protocol 0 (commonly referred to as being "text")
Correct code based on orignal example in question:
file = open("test.txt", 'wb') thing = {'a': 1, 'b':2} cPickle.dump(thing, file)
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