This snippet updates http://www.djangosnippets.org/snippets/383/ and http://www.djangosnippets.org/snippets/1495/ for Django 1.4+, and adds support for sqlite3 and south. Original snippet text: A CompressedTextField to transparently save data gzipped in the database and uncompress at retrieval.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 | # -*- coding: utf-8 -*-
# http://www.djangosnippets.org/snippets/383/
# Source: http://djangosnippets.org/snippets/1495/
from django.db import models
from django.utils.text import compress_string
from django.db.models.signals import post_init
def uncompress_string(s):
"""helper function to reverse django.utils.text.compress_string"""
import cStringIO, gzip
try:
val = s.encode('utf').decode('base64')
zbuf = cStringIO.StringIO(val)
zfile = gzip.GzipFile(fileobj=zbuf)
ret = zfile.read()
zfile.close()
except:
ret = s
return ret
class CompressedTextField(models.TextField):
"""transparently compress data before hitting the db and uncompress after fetching"""
def get_db_prep_save(self, value, connection):
if value is not None:
if isinstance(value, unicode):
value = value.encode('utf8')
value = compress_string(value)
value = value.encode('base64').decode('utf8')
return models.TextField.get_db_prep_save(self, value, connection=connection)
def _get_val_from_obj(self, obj):
if obj:
value = uncompress_string(getattr(obj, self.attname))
if value is not None:
try:
value = value.decode('utf8')
except UnicodeDecodeError:
pass
return value
else:
return self.get_default()
else:
return self.get_default()
def post_init(self, instance=None, **kwargs):
value = self._get_val_from_obj(instance)
if value:
setattr(instance, self.attname, value)
def contribute_to_class(self, cls, name):
super(CompressedTextField, self).contribute_to_class(cls, name)
post_init.connect(self.post_init, sender=cls)
def get_internal_type(self):
return "TextField"
def db_type(self):
from django.conf import settings
db_types = {'django.db.backends.mysql':'longblob', 'django.db.backends.sqlite3':'blob'}
try:
return db_types[settings.DATABASES['default']['ENGINE']]
except KeyError:
raise Exception, '%s currently works only with: %s'%(self.__class__.__name__,','.join(db_types.keys()))
def south_field_triple(self):
"""Returns a suitable description of this field for South."""
# We'll just introspect the _actual_ field.
from south.modelsinspector import introspector
field_class = "django.db.models.fields.TextField"
args, kwargs = introspector(self)
# That's our definition!
return (field_class, args, kwargs)
|
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Comments
Remember to add connection to db_type:
def db_type(self, connection):
#
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