from django.db.utils import ConnectionHandler, ConnectionRouter, load_backend, DEFAULT_DB_ALIAS, \

                            DatabaseError, IntegrityError

__all__ = ('backend', 'connection', 'connections', 'router', 'DatabaseError',

    'IntegrityError', 'DEFAULT_DB_ALIAS')

# For backwards compatibility - Port any old database settings over to

# the new values.

if not settings.DATABASES:

    import warnings

    warnings.warn(

        "settings.DATABASE_* is deprecated; use settings.DATABASES instead.",

        PendingDeprecationWarning

    )

    settings.DATABASES[DEFAULT_DB_ALIAS] = {

        'ENGINE': settings.DATABASE_ENGINE,

        'HOST': settings.DATABASE_HOST,

        'NAME': settings.DATABASE_NAME,

        'OPTIONS': settings.DATABASE_OPTIONS,

        'PASSWORD': settings.DATABASE_PASSWORD,

        'PORT': settings.DATABASE_PORT,

        'USER': settings.DATABASE_USER,

        'TEST_CHARSET': settings.TEST_DATABASE_CHARSET,

        'TEST_COLLATION': settings.TEST_DATABASE_COLLATION,

        'TEST_NAME': settings.TEST_DATABASE_NAME,

    }

if DEFAULT_DB_ALIAS not in settings.DATABASES:

    raise ImproperlyConfigured("You must default a '%s' database" % DEFAULT_DB_ALIAS)

for alias, database in settings.DATABASES.items():

    if database['ENGINE'] in ("postgresql", "postgresql_psycopg2", "sqlite3", "mysql", "oracle"):

        import warnings

        if 'django.contrib.gis' in settings.INSTALLED_APPS:

            warnings.warn(

                "django.contrib.gis is now implemented as a full database backend. "

                "Modify ENGINE in the %s database configuration to select "

                "a backend from 'django.contrib.gis.db.backends'" % alias,

                PendingDeprecationWarning

            )

            if database['ENGINE'] == 'postgresql_psycopg2':

                full_engine = 'django.contrib.gis.db.backends.postgis'

            elif database['ENGINE'] == 'sqlite3':

                full_engine = 'django.contrib.gis.db.backends.spatialite'

                full_engine = 'django.contrib.gis.db.backends.%s' % database['ENGINE']

        else:

            warnings.warn(

                "Short names for ENGINE in database configurations are deprecated. "

                "Prepend %s.ENGINE with 'django.db.backends.'" % alias,

                PendingDeprecationWarning

            )

            full_engine = "django.db.backends.%s" % database['ENGINE']

        database['ENGINE'] = full_engine

connections = ConnectionHandler(settings.DATABASES)

router = ConnectionRouter(settings.DATABASE_ROUTERS)

# we load all these up for backwards compatibility, you should use

# connections['default'] instead.

connection = connections[DEFAULT_DB_ALIAS]

backend = load_backend(connection.settings_dict['ENGINE'])

    for conn in connections.all():

        conn.close()

    for conn in connections.all():

        conn.queries = []

# Register an event that rolls back the connections

    for conn in connections:

        try:

            transaction.rollback_unless_managed(using=conn)

        except DatabaseError:

            pass