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 import inspect
  20
  21 from mediagoblin.tools.transition import DISABLE_GLOBALS
  22
  23 if not DISABLE_GLOBALS:
  24     from sqlalchemy.orm import scoped_session, sessionmaker
  25     Session = scoped_session(sessionmaker())
  26
  27
  28 class GMGTableBase(object):
  29     @property
  30     def _session(self):
  31         return inspect(self).session
  32
  33     @property
  34     def _app(self):
  35         return self._session.bind.app
  36
  37     if not DISABLE_GLOBALS:
  38         query = Session.query_property()
  39
  40     def get(self, key):
  41         return getattr(self, key)
  42
  43     def setdefault(self, key, defaultvalue):
  44         # The key *has* to exist on sql.
  45         return getattr(self, key)
  46
  47     def save(self, commit=True):
  48         sess = self._session
  49         if sess is None and not DISABLE_GLOBALS:
  50             sess = Session()
  51         assert sess is not None, "Can't save, %r has a detached session" % self
  52         sess.add(self)
  53         if commit:
  54             sess.commit()
  55         else:
  56             sess.flush()
  57
  58     def delete(self, commit=True):
  59         """Delete the object and commit the change immediately by default"""
  60         sess = self._session
  61         assert sess is not None, "Not going to delete detached %r" % self
  62         sess.delete(self)
  63         if commit:
  64             sess.commit()
  65
  66
  67 Base = declarative_base(cls=GMGTableBase)
  68
  69
  70 class DictReadAttrProxy(object):
  71     """
  72     Maps read accesses to obj['key'] to obj.key
  73     and hides all the rest of the obj
  74     """
  75     def __init__(self, proxied_obj):
  76         self.proxied_obj = proxied_obj
  77
  78     def __getitem__(self, key):
  79         try:
  80             return getattr(self.proxied_obj, key)
  81         except AttributeError:
  82             raise KeyError("%r is not an attribute on %r"
  83                 % (key, self.proxied_obj))