q3stats/q3stats/database.py

# -*- coding: utf-8 -*-
# Copyright (c) 2017 Tomek Wójcik <tomek@bthlabs.pl>
#
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"""
q3stats.database
================

This module contains database utilities.
"""

import sqlalchemy as sa
from sqlalchemy.ext.declarative import declarative_base

#: Base for declarative models
Base = declarative_base()

#: Current SQLAlchemy engine
db_engine = None

#: Current SQLAlchemy session
db_session = None


def create_engine(config):
    """Creates and initializes engine according to *config* dictionary.

    Returns the initialized engine."""
    engine = sa.create_engine(
        config['SQLALCHEMY_URL'], **config.get('SQLALCHEMY_OPTS', {})
    )

    return engine


def create_session(engine, config, scoped=True):
    """Creates a session factory bound to *engine* according to *config*
    dictionary. If *scoped* is ``True`` then the session will be scoped.
    Otherwise, it'll be a standard ``sessionmaker``.

    Returns the initialized session factory."""
    Session = sa.orm.sessionmaker(
        bind=engine, **config.get('SQLALCHEMY_SESSION_OPTS', {})
    )

    if scoped:
        return sa.orm.scoped_session(Session)

    return Session