straight forward django database adapter for mongoengine

mongodb.py

# mongoengine's database instance
import urlparse

from django.conf import settings
from django.core.exceptions import ImproperlyConfigured

# cached mongodb instances, by alias
_mongodb = {}


def connect(alias='mongodb'):
    """
    straight forward django database adapter for mongodb

    requires mongoengine

    This will define a mongodb connection with deferred access. Place
    somewhere loaded on startup, or use within code where needed. Connections
    are pooled by mongoengine. 

    Usage:
        # settings
        DATABASES = {
            'mongodb' : {
               'URL' : 'mongodb://host:port/database',
               'OPTIONS' : {
                   'param' : 'value'
               }
            }
        }

        instead of 'mongodb' any other alias can be used. multiple aliases
        are supported. If not configured, the default database is 
        mongodb://localhost/django 

        OPTIONS is optional. specify any kwargs that 
        mongoengine.connect() supports. If not specified the following 
        defaults are applied:

        connect=False # defer connection until first access
        serverSelectionTimeoutMS=2500 # fail fast if connection is not available
    """
    try:
        import mongoengine  # @UnresolvedImport
    except:
        raise ImproperlyConfigured(
            "Cannot import mongoengine. Is it installed?")
    _db = _mongodb.get(alias)
    if _db is not None:
        return _db
    default_config = {
        'URL': 'mongodb://localhost/django',
    }
    dbconfig = settings.DATABASES.get(alias, default_config)
    try:
        mongo_url = dbconfig.get('URL')
        parsed_url = urlparse.urlparse(mongo_url)
        database_name = parsed_url.path[1:]
    except Exception as e:
        msg = "Cannot get or parse URL in settings.DATABASES['%s'], %s" % (
            alias, e)
        raise ImproperlyConfigured(msg)
    # connect via mongoengine
    # note this uses a MongoClient in the background, with pooled
    # connections. there are multiprocessing issues with pymongo:
    # http://api.mongodb.org/python/3.2/faq.html#using-pymongo-with-multiprocessing
    # connect=False is due to https://jira.mongodb.org/browse/PYTHON-961
    # this defers connecting until the first access
    # serverSelectionTimeoutMS=2500 is to fail fast, the default is 30000
    options = dbconfig.get('OPTIONS', {})
    options.setdefault('connect', False)
    options.setdefault('serverSelectionTimeoutMS', 2500)
    _db = getattr(mongoengine.connect(database_name,
                                      host=mongo_url,
                                      alias=alias,
                                      **options),
                  database_name)
    # cache db instance
    _mongodb[alias] = _db
    return _db