source: OpenRLabs-Git/deploy/rlabs-docker/web2py-rlabs/gluon/contrib/heroku.py

"""
Usage: in web2py models/db.py

from gluon.contrib.heroku import get_db
db = get_db()

"""
import os
from gluon import *
from pydal.adapters import adapters, PostgrePsyco
from pydal.helpers.classes import DatabaseStoredFile

@adapters.register_for('postgres')
class HerokuPostgresAdapter(DatabaseStoredFile, PostgrePsyco):
    uploads_in_blob = True

def get_db(name = None, pool_size=10):
    if not name:
        names = [n for n in os.environ.keys()
                 if n[:18]+n[-4:]=='HEROKU_POSTGRESQL__URL']
        if names:
            name = names[0]
    if name:
        db = DAL(os.environ[name], pool_size=pool_size)
        current.session.connect(current.request, current.response, db=db)
    else:
        db = DAL('sqlite://heroku.test.sqlite')
    return db