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# -*- coding: utf-8 -*-
from django.db import models
import cPickle as pickle
except ImportError:
import pickle
class PickledObject(str):
"""A subclass of string so it can be told whether a string is
a pickled object or not (if the object is an instance of this class
then it must [well, should] be a pickled one)."""
class PickledObjectField(models.Field):
__metaclass__ = models.SubfieldBase
def to_python(self, value):
if isinstance(value, PickledObject):
# If the value is a definite pickle; and an error is raised in de-pickling
# it should be allowed to propogate.
return pickle.loads( str(value).decode('base64') )
return pickle.loads( str(value).decode('base64') )
# If an error was raised, just return the plain value
return value
def get_db_prep_save(self, value):
if value is not None and not isinstance(value, PickledObject):
value = PickledObject( pickle.dumps(value).encode('base64') )
return value
def get_internal_type(self):
return 'TextField'
def get_db_prep_lookup(self, lookup_type, value):
if lookup_type == 'exact':
value = self.get_db_prep_save(value)
return super(PickledObjectField, self).get_db_prep_lookup(lookup_type, value)
elif lookup_type == 'in':
value = [self.get_db_prep_save(v) for v in value]
return super(PickledObjectField, self).get_db_prep_lookup(lookup_type, value)
raise TypeError('Lookup type %s is not supported.' % lookup_type)