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@@ -1,153 +0,0 @@
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-"""
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-
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-Custom Django Model Fields.
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-
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-"""
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-
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-from copy import deepcopy
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-from base64 import b64encode, b64decode
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-from zlib import compress, decompress
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-try:
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- import cPickle as pickle
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-except ImportError:
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- import pickle
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-
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-from django.db import models
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-from django.utils.encoding import force_unicode
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-
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-
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-class PickledObject(str):
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- """A subclass of string so it can be told whether a string is a pickled
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- object or not (if the object is an instance of this class then it must
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- [well, should] be a pickled one).
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-
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- Only really useful for passing pre-encoded values to ``default``
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- with ``dbsafe_encode``, not that doing so is necessary. If you
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- remove PickledObject and its references, you won't be able to pass
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- in pre-encoded values anymore, but you can always just pass in the
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- python objects themselves.
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-
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- """
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- pass
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-
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-
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-def dbsafe_encode(value, compress_object=False):
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- """We use deepcopy() here to avoid a problem with cPickle, where dumps
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- can generate different character streams for same lookup value if
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- they are referenced differently.
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-
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- The reason this is important is because we do all of our lookups as
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- simple string matches, thus the character streams must be the same
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- for the lookups to work properly. See tests.py for more
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- information.
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-
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- """
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- if not compress_object:
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- value = b64encode(pickle.dumps(deepcopy(value)))
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- else:
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- value = b64encode(compress(pickle.dumps(deepcopy(value))))
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- return PickledObject(value)
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-
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-
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-def dbsafe_decode(value, compress_object=False):
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- if not compress_object:
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- value = pickle.loads(b64decode(value))
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- else:
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- value = pickle.loads(decompress(b64decode(value)))
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- return value
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-
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-
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-class PickledObjectField(models.Field):
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- """A field that will accept *any* python object and store it in the
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- database. PickledObjectField will optionally compress it's values if
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- declared with the keyword argument ``compress=True``.
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-
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- Does not actually encode and compress ``None`` objects (although you
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- can still do lookups using None). This way, it is still possible to
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- use the ``isnull`` lookup type correctly. Because of this, the field
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- defaults to ``null=True``, as otherwise it wouldn't be able to store
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- None values since they aren't pickled and encoded.
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-
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- """
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- __metaclass__ = models.SubfieldBase
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-
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- def __init__(self, *args, **kwargs):
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- self.compress = kwargs.pop('compress', False)
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- self.protocol = kwargs.pop('protocol', 2)
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- kwargs.setdefault('null', True)
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- kwargs.setdefault('editable', False)
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- super(PickledObjectField, self).__init__(*args, **kwargs)
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-
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- def get_default(self):
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- """Returns the default value for this field.
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-
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- The default implementation on models.Field calls force_unicode
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- on the default, which means you can't set arbitrary Python
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- objects as the default. To fix this, we just return the value
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- without calling force_unicode on it. Note that if you set a
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- callable as a default, the field will still call it. It will
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- *not* try to pickle and encode it.
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-
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- """
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- if self.has_default():
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- if callable(self.default):
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- return self.default()
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- return self.default
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- # If the field doesn't have a default, then we punt to models.Field.
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- return super(PickledObjectField, self).get_default()
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-
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- def to_python(self, value):
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- """B64decode and unpickle the object, optionally decompressing it.
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-
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- If an error is raised in de-pickling and we're sure the value is
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- a definite pickle, the error is allowed to propogate. If we
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- aren't sure if the value is a pickle or not, then we catch the
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- error and return the original value instead.
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-
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- """
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-
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- if value is not None:
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- try:
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- value = dbsafe_decode(value, self.compress)
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- except:
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- # If the value is a definite pickle; and an error is raised in
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- # de-pickling it should be allowed to propogate.
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- if isinstance(value, PickledObject):
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- raise
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- return value
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-
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- def get_db_prep_value(self, value):
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- """Pickle and b64encode the object, optionally compressing it.
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-
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- The pickling protocol is specified explicitly (by default 2),
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- rather than as -1 or HIGHEST_PROTOCOL, because we don't want the
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- protocol to change over time. If it did, ``exact`` and ``in``
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- lookups would likely fail, since pickle would now be generating
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- a different string.
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-
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- """
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-
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- if value is not None and not isinstance(value, PickledObject):
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- # We call force_unicode here explicitly, so that the encoded
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- # string isn't rejected by the postgresql_psycopg2 backend.
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- # Alternatively, we could have just registered PickledObject with
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- # the psycopg marshaller (telling it to store it like it would a
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- # string), but since both of these methods result in the same
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- # value being stored, doing things this way is much easier.
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- value = force_unicode(dbsafe_encode(value, self.compress))
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- return value
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-
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- def value_to_string(self, obj):
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- value = self._get_val_from_obj(obj)
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- return self.get_db_prep_value(value)
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-
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- def get_internal_type(self):
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- return 'TextField'
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-
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- def get_db_prep_lookup(self, lookup_type, value):
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- if lookup_type not in ['exact', 'in', 'isnull']:
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- raise TypeError('Lookup type %s is not supported.' % lookup_type)
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- # The Field model already calls get_db_prep_value before doing the
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- # actual lookup, so all we need to do is limit the lookup types.
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- return super(PickledObjectField, self).get_db_prep_lookup(lookup_type,
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- value)
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