db_init.py

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker
from config import ProductionDevelopmentConfig
from sqlalchemy import event
from utils.validators import validators
from flask import g

# db_session = g.db

# see this: http://flask.pocoo.org/docs/0.10/patterns/sqlalchemy/
# engine = create_engine(app.config['SQLALCHEMY_DATABASE_URI'])
# engine = create_engine(ProductionDevelopmentConfig.SQLALCHEMY_DATABASE_URI)
# db_session = scoped_session(sessionmaker(autocommit=False,
#                                          autoflush=False,
#                                          bind=engine))
# Base = declarative_base()
#
# # this event is called whenever an attribute
# # on a class is instrumented
# @event.listens_for(Base, 'attribute_instrument')
# def configure_listener(class_, key, inst):
#     if not hasattr(inst.property, 'columns'):
#         return
#     # this event is called whenever a "set"
#     # occurs on that instrumented attribute
#
#     @event.listens_for(inst, "set", retval=True)
#     def set_(instance, value, oldvalue, initiator):
#         validator = validators.get(inst.property.columns[0].type.__class__)
#         if validator:
#             return validator(value)
#         else:
#             return value
#
# Base.query = db_session.query_property()