db

import sqlsoup
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker


def singleton(cls, *args, **kwargs):
    instances = {}

    def get_instance():
        if cls not in instances:
            instances[cls] = cls(*args, **kwargs)
        return instances[cls]
    return get_instance


@singleton
class Engine(object):
    def __new__(cls, *args, **kwargs):
        config = {
            'host': 'localhost',
            'database': 'demo',
            'username': 'root',
            'password': '123456',
        }
        _tpl = 'mysql://{username}:{password}@{host}/{database}?charset=utf8'
        connect_url = _tpl.format(**config)
        engine = create_engine(connect_url,
                               strategy='threadlocal',
                               pool_size=5,
                               pool_recycle=1800,
                               encoding='utf-8',
                               max_overflow=2)
        return engine


db = sqlsoup.SQLSoup(Engine(), session=scoped_session(sessionmaker(autoflush=False,
                                                                   expire_on_commit=False,
                                                                   autocommit=True)))