openmedialibrary/oml/db.py

from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.mutable import Mutable
from sqlalchemy.ext.declarative import declarative_base
import settings


engine = create_engine('sqlite:////%s' % settings.db_path)
Session = sessionmaker(bind=engine)

# create a Session
session = Session()


Model = declarative_base()


class MutableDict(Mutable, dict):
    @classmethod
    def coerce(cls, key, value):
        "Convert plain dictionaries to MutableDict."

        if not isinstance(value, MutableDict):
            if isinstance(value, dict):
                return MutableDict(value)

            # this call will raise ValueError
            return Mutable.coerce(key, value)
        else:
            return value

    def __setitem__(self, key, value):
        "Detect dictionary set events and emit change events."

        dict.__setitem__(self, key, value)
        self.changed()

    def __delitem__(self, key):
        "Detect dictionary del events and emit change events."

        dict.__delitem__(self, key)
        self.changed()