dbcache.py

   1 class Cache(object):
   2
   3     def __init__(self, cls, attr, session):
   4         self.cls = cls
   5         self.attr = attr
   6         self._cache = {}
   7         self.session = session
   8
   9     def __getitem__(self, key):
  10         try:
  11             return self._cache[key]
  12         except KeyError:
  13             pass
  14         v = self.session.query(self.cls).filter(self.attr==key).first()
  15         if not v:
  16             raise KeyError
  17         self._cache[key] = v
  18         return v
  19
  20     def __contains__(self, key):
  21         try:
  22             v = self[key]
  23         except KeyError:
  24             return False
  25         return True
  26
  27     def get(self, key):
  28         try:
  29             v = self[key]
  30         except KeyError:
  31             v = self.cls(key)
  32             self._cache[key] = v
  33             self.session.add(v)
  34         return v