mediagoblin/db/base.py

   1 # GNU MediaGoblin -- federated, autonomous media hosting
   2 # Copyright (C) 2011, 2012 MediaGoblin contributors.  See AUTHORS.
   3 #
   4 # This program is free software: you can redistribute it and/or modify
   5 # it under the terms of the GNU Affero General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU Affero General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU Affero General Public License
  15 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17
  18 from sqlalchemy.ext.declarative import declarative_base
  19 from sqlalchemy.orm import scoped_session, sessionmaker, object_session
  20
  21 Session = scoped_session(sessionmaker())
  22
  23
  24 class GMGTableBase(object):
  25     query = Session.query_property()
  26
  27     def get(self, key):
  28         return getattr(self, key)
  29
  30     def setdefault(self, key, defaultvalue):
  31         # The key *has* to exist on sql.
  32         return getattr(self, key)
  33
  34     def save(self):
  35         sess = object_session(self)
  36         if sess is None:
  37             sess = Session()
  38         sess.add(self)
  39         sess.commit()
  40
  41     def delete(self, commit=True):
  42         """Delete the object and commit the change immediately by default"""
  43         sess = object_session(self)
  44         assert sess is not None, "Not going to delete detached %r" % self
  45         sess.delete(self)
  46         if commit:
  47             sess.commit()
  48
  49
  50 Base = declarative_base(cls=GMGTableBase)
  51
  52
  53 class DictReadAttrProxy(object):
  54     """
  55     Maps read accesses to obj['key'] to obj.key
  56     and hides all the rest of the obj
  57     """
  58     def __init__(self, proxied_obj):
  59         self.proxied_obj = proxied_obj
  60
  61     def __getitem__(self, key):
  62         try:
  63             return getattr(self.proxied_obj, key)
  64         except AttributeError:
  65             raise KeyError("%r is not an attribute on %r"
  66                 % (key, self.proxied_obj))