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R3600/invenio/ext/sqlalchemy/types/marshal_binary.py
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marshal_binary.py
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# -*- coding: utf-8 -*-
#
## This file is part of Invenio.
## Copyright (C) 2011, 2012, 2013, 2014 CERN.
##
## Invenio is free software; you can redistribute it and/or
## modify it under the terms of the GNU General Public License as
## published by the Free Software Foundation; either version 2 of the
## License, or (at your option) any later version.
##
## Invenio is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Invenio; if not, write to the Free Software Foundation, Inc.,
## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
"""Implement compressed column type."""
from sqlalchemy.types import TypeDecorator, LargeBinary
from invenio.utils.serializers import ZlibMarshal
class MarshalBinary(TypeDecorator):
"""Implement compressed column type."""
impl = LargeBinary
def __init__(self, default_value, force_type=None, *args, **kwargs):
"""Initialize default value and type."""
super(MarshalBinary, self).__init__(*args, **kwargs)
self.default_value = default_value
self.force_type = force_type if force_type is not None else lambda x: x
def process_bind_param(self, value, dialect):
"""Compress data in column."""
if value is not None:
value = ZlibMarshal.dumps(self.force_type(value))
return value
return value
def process_result_value(self, value, dialect):
"""Load comressed data from column."""
if value is not None:
try:
value = ZlibMarshal.loads(value)
except:
value = None
return value if value is not None else \
(self.default_value() if callable(self.default_value) else
self.default_value)
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