Refactor blob cache code into separate module

[trackgit.git] / dbcache.py

class Cache(object):

    def __init__(self, cls, attr, session):
        self.cls = cls
        self.attr = attr
        self._cache = {}
        self.session = session

    def __getitem__(self, key):
        try:
            return self._cache[key]
        except KeyError:
            pass
        v = session.query(self.cls).filter(self.attr==key).first()
        if not v:
            raise KeyError
        self._cache[key] = v
        return v

    def get(self, key):
        try:
            v = self[key]
        except KeyError:
            v = cls(key)
            self._cache[key] = v
            session.add(v)
        return v