Pickle or json?

Question

I need to save to disk a little dict object which keys are strings and values are ints and then recover it. Something like this:

{'juanjo': 2, 'pedro':99, 'other': 333}

Which and why is the best option? Serialize it with pickle or with simplejson?

I'm using Python 2.6

Answer 1

If you do not have any interoperability requirements (i.e. you're just going to use the data with Python), and a binary format is fine, go with cPickle, which gives you really fast Python object serialization.

If you want interoperability, or you want a text format to store your data, go with JSON (or some other appropriate format depending on your constraints).

Answer 2

I prefer JSON over pickle for my serialization. Unpickling can run arbitrary code, and using pickle to transfer data between programs or store data between sessions is a security hole. JSON does not introduce a security hole and is standardized, so the data can be accessed by programs in different languages if you ever need to.

Answer 3

Json or pickle? How about json and pickle! You can use jsonpickle. It easy to use and the file on disk is readable because it's json.

http://jsonpickle.github.com/

Answer 4

Later on one may want to persist some arbitrary Python object. In that case, clearly cPickle plus compression offers speed. Take a look at:

y_serial.py module :: warehouse Python objects with SQLite

"Serialization + persistance :: in a few lines of code, compress and annotate Python objects into SQLite; then later retrieve them chronologically by keywords without any SQL. Most useful "standard" module for a database to store schema-less data."

http://yserial.sourceforge.net

The security issue is also carefully addressed in the internal documentation. This Python module has broad application, and it's very easy to implement < 10 minutes.