Wrapper around shelve.DbfilenameShelf that ensure Unicode strings are properly encoded/decoded before being inserted/after being extracted from the database.

UnicodeShelve

#!/usr/bin/python

import shelve


class UnicodeShelve(shelve.DbfilenameShelf, object):
    """Wrapper around shelve.DbfilenameShelf that ensure unicode strings
    are properly encoded/decoded before being insered/after being extracted
    from the database."""

    def __deep_convert(self, it, decode=False):
        if isinstance(it, list):
            return [self.__deep_convert(e) for e in it]
        if isinstance(it, tuple):
            return tuple([self.__deep_convert(e) for e in it])
        if isinstance(it, dict):
            return {self.__deep_convert(k):self. __deep_convert(v)
                    for k, v in it.iteritems()}
        try:
            return it.encode('utf-8') if not decode else it.decode('utf-8')
        except AttributeError:
            return it

    def __setitem__(self, key, val):
        key_enc = self.__deep_convert(key)
        val_enc = self.__deep_convert(val)
        super(UnicodeShelve, self).__setitem__(key_enc, val_enc)

    def __getitem__(self, key):
        key_enc = self.__deep_convert(key)
        val_enc = super(UnicodeShelve, self).__getitem__(key_enc)
        return self.__deep_convert(val_enc, decode=True)

    def __contains__(self, value):
        value_enc = self.__deep_convert(value)
        return super(UnicodeShelve, self).__contains__(value_enc)