Created
June 24, 2011 15:39
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copy snippet PickleField and add ZipPickleField Field for large sizing objects
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# -*- coding: utf-8 -*- | |
from django.db import models | |
import zlib | |
try: | |
import cPickle as pickle | |
except ImportError: | |
import pickle | |
from south.modelsinspector import add_introspection_rules | |
add_introspection_rules([], ["^b2b\.fields\.PickledObjectField"]) | |
add_introspection_rules([], ["^b2b\.fields\.ZipPickledObjectField"]) | |
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).""" | |
pass | |
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)) | |
else: | |
try: | |
return pickle.loads(str(value)) | |
except: | |
# 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)) | |
return value | |
def get_internal_type(self): | |
return 'TextField' | |
def db_type(self): | |
return 'longblob' #mysql | |
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) | |
else: | |
raise TypeError('Lookup type %s is not supported.' % lookup_type) | |
class ZipPickledObjectField(PickledObjectField): | |
def to_python(self, value): | |
try: | |
value = zlib.decompress(value) | |
except: | |
#if value decompressed! | |
pass | |
return super(ZipPickledObjectField, self).to_python(value) | |
def get_db_prep_save(self, value): | |
value = super(ZipPickledObjectField, self).get_db_prep_save(value) | |
if value is not None: | |
value = zlib.compress(value, 9) | |
return value |
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