This document describes the current stable version of Celery (3.1). For development docs, go here.
Source code for celery.backends
# -*- coding: utf-8 -*-
"""
celery.backends
~~~~~~~~~~~~~~~
Backend abstract factory (...did I just say that?) and alias definitions.
"""
from __future__ import absolute_import
import sys
import types
from celery.exceptions import ImproperlyConfigured
from celery.local import Proxy
from celery._state import current_app
from celery.five import reraise
from celery.utils.imports import symbol_by_name
__all__ = ['get_backend_cls', 'get_backend_by_url']
UNKNOWN_BACKEND = """\
Unknown result backend: {0!r}. Did you spell that correctly? ({1!r})\
"""
BACKEND_ALIASES = {
'amqp': 'celery.backends.amqp:AMQPBackend',
'rpc': 'celery.backends.rpc.RPCBackend',
'cache': 'celery.backends.cache:CacheBackend',
'redis': 'celery.backends.redis:RedisBackend',
'mongodb': 'celery.backends.mongodb:MongoBackend',
'db': 'celery.backends.database:DatabaseBackend',
'database': 'celery.backends.database:DatabaseBackend',
'cassandra': 'celery.backends.cassandra:CassandraBackend',
'couchbase': 'celery.backends.couchbase:CouchBaseBackend',
'disabled': 'celery.backends.base:DisabledBackend',
}
#: deprecated alias to ``current_app.backend``.
default_backend = Proxy(lambda: current_app.backend)
[docs]def get_backend_cls(backend=None, loader=None):
"""Get backend class by name/alias"""
backend = backend or 'disabled'
loader = loader or current_app.loader
aliases = dict(BACKEND_ALIASES, **loader.override_backends)
try:
cls = symbol_by_name(backend, aliases)
except ValueError as exc:
reraise(ImproperlyConfigured, ImproperlyConfigured(
UNKNOWN_BACKEND.format(backend, exc)), sys.exc_info()[2])
if isinstance(cls, types.ModuleType):
raise ImproperlyConfigured(UNKNOWN_BACKEND.format(
backend, 'is a Python module, not a backend class.'))
return cls
[docs]def get_backend_by_url(backend=None, loader=None):
url = None
if backend and '://' in backend:
url = backend
scheme, _, _ = url.partition('://')
if '+' in scheme:
backend, url = url.split('+', 1)
else:
backend = scheme
return get_backend_cls(backend, loader), url