Result backend not registered?

[Baekalfen]

I've tried to set up a minimal setup with a result backend, but I still get an error message, that the middleware is not loaded.

Django, Redis and Dramatiq are all running in individual docker containers. Dramatiq is started with python manage.py rundramatiq.

Settings:

DRAMATIQ_BROKER = {
    "BROKER": "dramatiq.brokers.rabbitmq.RabbitmqBroker",
    "OPTIONS": {
        "url": BROKER_URL,
    },
    "MIDDLEWARE": [
        "dramatiq.middleware.Prometheus",
        "dramatiq.middleware.AgeLimit",
        "dramatiq.middleware.TimeLimit",
        "dramatiq.middleware.Callbacks",
        "dramatiq.middleware.Retries",
        "django_dramatiq.middleware.AdminMiddleware",
        "django_dramatiq.middleware.DbConnectionsMiddleware",
    ]
}

DRAMATIQ_RESULT_BACKEND = {
    "BACKEND": "dramatiq.results.backends.redis.RedisBackend",
    "BACKEND_OPTIONS": {
        "url": "redis://redis:6379",
    }
}

If I send a task using the Django shell, I see the following in the log:

dramatiq_1      | Pushing message '8c87e639-342b-4c9b-81ad-56997f6a729f' onto work queue.
dramatiq_1      | Received message test_actor('123') with id '8c87e639-342b-4c9b-81ad-56997f6a729f'.
dramatiq_1      | Updating Task from message '8c87e639-342b-4c9b-81ad-56997f6a729f'.
postgres_1      | 2020-07-13 13:50:56.669 UTC [72] ERROR:  duplicate key value violates unique constraint "django_dramatiq_task_pkey"
postgres_1      | 2020-07-13 13:50:56.669 UTC [72] DETAIL:  Key (id)=(8c87e639-342b-4c9b-81ad-56997f6a729f) already exists.
postgres_1      | 2020-07-13 13:50:56.669 UTC [72] STATEMENT:  INSERT INTO "django_dramatiq_task" ("id", "status", "created_at", "updated_at", "message_data", "actor_name", "queue_name") VALUES ('8c87e639-342b-4c9b-81ad-56997f6a729f'::uuid, 'running', '2020-07-13T13:50:56.668878+00:00'::timestamptz, '2020-07-13T13:50:56.669010+00:00'::timestamptz, '\x7b2271756575655f6e616d65223a2264656661756c74222c226163746f725f6e616d65223a22746573745f6163746f72222c2261726773223a5b22313233225d2c226b7761726773223a7b7d2c226f7074696f6e73223a7b7d2c226d6573736167655f6964223a2238633837653633392d333432622d346339622d383161642d353639393766366137323966222c226d6573736167655f74696d657374616d70223a313539343634383235363539327d'::bytea, 'test_actor', 'default')
dramatiq_1      | Received args=('123',) kwargs={}.
dramatiq_1      | Actor 'test_actor' returns a value that is not None, and you haven't added the Results middleware to the broker, which means the return value will be silently dropped. Consider adding the Results middleware to your broker.
dramatiq_1      | Completed after 0.40ms.
dramatiq_1      | Updating Task from message '8c87e639-342b-4c9b-81ad-56997f6a729f'.
dramatiq_1      | Acknowledging message '8c87e639-342b-4c9b-81ad-56997f6a729f'.

[Baekalfen]

I've tried to add some print statements in apps.py, and I can see that the settings are picked up and the middleware is supposedly loaded, when I run python manage.py shell

[Bogdanp]

The warning might be mis-diagnosing the problem. Are you passing store_results=True to @actor(...)?

[Baekalfen]

Ah, that was it! Thank you!