SynchronousOnlyOperation django app ready and database call failed

[kojibhy]

from django.apps import AppConfig

def refresh_cache_from_db():
    from test_app.models import TestModel
     for c in TestModel.objects.all():
         redis_cache_store.set(c.name, c, timeout=None)

 
class TestConfig(AppConfig):
    name = 'applications.test'

    def ready(self):
        refresh_cache_from_db()

wsgi.py works perfect but asgi.py channels will failed with error django.core.exceptions.SynchronousOnlyOperation: You cannot call this from an async context - use a thread or sync_to_async.

in my app i use wsgi.py for handle requests and asgi.py only for websockets how to solve this problem?

[carltongibson]

Can you post the whole traceback please

[kojibhy]

|   File "/app/./core/asgi.py", line 9, in <module>
|     django_asgi_app = get_asgi_application()
|   File "/usr/local/lib/python3.10/site-packages/django/core/asgi.py", line 12, in get_asgi_application
|     django.setup(set_prefix=False)
|   File "/usr/local/lib/python3.10/site-packages/django/__init__.py", line 24, in setup
|     apps.populate(settings.INSTALLED_APPS)
|   File "/usr/local/lib/python3.10/site-packages/django/apps/registry.py", line 124, in populate
|     app_config.ready()
|   File "/app/project/test/apps.py", line 12, in ready
|     redis_from_db_refresh()
|   File "/app/project/test/services/redis_build_cache.py", line 14, in redis_from_db_refresh
|     for i in TestModel.objects.all():
|   File "/usr/local/lib/python3.10/site-packages/django/db/models/query.py", line 320, in __iter__
|     self._fetch_all()
|   File "/usr/local/lib/python3.10/site-packages/django/db/models/query.py", line 1507, in _fetch_all
|     self._result_cache = list(self._iterable_class(self))
|   File "/usr/local/lib/python3.10/site-packages/django/db/models/query.py", line 57, in __iter__
|     results = compiler.execute_sql(
|   File "/usr/local/lib/python3.10/site-packages/django/db/models/sql/compiler.py", line 1359, in execute_sql
|     cursor = self.connection.cursor()
|   File "/usr/local/lib/python3.10/site-packages/django/utils/asyncio.py", line 24, in inner
|     raise SynchronousOnlyOperation(message)
| django.core.exceptions.SynchronousOnlyOperation: You cannot call this from an async context - use a thread or sync_to_async.

[carltongibson]

Yes... OK...

Making DB queries in ready() is not supported. See the warning in the AppConfig.ready docs

I'd move this logic to your project's wsgi.py and asgi.py files respectively, using sync_to_async() in the latter case.