Hi,
I am attempting to upgrade from Django 3.0 to 3.1 and asgiref 2.x to 3.x,
and noticed a breakage in a view which I suspect might be related to its
usage of StreamingHttpResponse. The code in question now raises the
following exception:
2020-12-08 17:50:05,159 [ERROR] daphne.server: Exception inside
application: You cannot call this from an async context - use a thread or
sync_to_async.
Traceback (most recent call last):
File "/usr/local/lib/python3.8/dist-packages/channels/staticfiles.py",
line 44, in __call__
return await self.application(scope, receive, send)
File "/usr/local/lib/python3.8/dist-packages/channels/routing.py", line
71, in __call__
return await application(scope, receive, send)
File
"/usr/local/lib/python3.8/dist-packages/django/core/handlers/asgi.py", line
168, in __call__
await self.send_response(response, send)
File
"/usr/local/lib/python3.8/dist-packages/django/core/handlers/asgi.py", line
242, in send_response
for part in response:
File "/main/srhaque/Innovatieltd/source/paiyroll/utils/time_machine.py",
line 202, in fill
for files in filler:
File
"/main/srhaque/Innovatieltd/source/paiyroll/views/employee/mobile_views.py",
line 636, in regenerate_documents
pay_run_db = models.PayRun.objects.get(id=pay_run['id'])
File "/usr/local/lib/python3.8/dist-packages/django/db/models/manager.py",
line 85, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/usr/local/lib/python3.8/dist-packages/django/db/models/query.py",
line 425, in get
num = len(clone)
File "/usr/local/lib/python3.8/dist-packages/django/db/models/query.py",
line 269, in __len__
self._fetch_all()
File "/usr/local/lib/python3.8/dist-packages/django/db/models/query.py",
line 1308, in _fetch_all
self._result_cache = list(self._iterable_class(self))
File
"/usr/local/lib/python3.8/dist-packages/django_viewflow-1.6.1-py3.8.egg/viewflow/managers.py",
line 79, in __iter__
for process in base_iterator:
File "/usr/local/lib/python3.8/dist-packages/django/db/models/query.py",
line 53, in __iter__
results = compiler.execute_sql(chunked_fetch=self.chunked_fetch,
chunk_size=self.chunk_size)
File
"/usr/local/lib/python3.8/dist-packages/django/db/models/sql/compiler.py",
line 1154, in execute_sql
cursor = self.connection.cursor()
File "/usr/local/lib/python3.8/dist-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.
(There is a subsequent exception, appended below, which I assume that is
caused by this exception). I see that the immediate cause of the problem is
the ORM query in my mobile_views.py, but I cannot seem to find the correct
way to wrap the query in sync_to_async() or database_sync_to_async(). Any
hints or pointers would be most welcome.
Thanks, Shaheed
Attachment: second exception for reference...
2020-12-08 17:50:05,168 [ERROR] asyncio: Exception in callback
AsyncioSelectorReactor.callLater.<locals>.run() at
/usr/local/lib/python3.8/dist-packages/twisted/internet/asyncioreactor.py:287
handle: <TimerHandle when=115234.625186167
AsyncioSelectorReactor.callLater.<locals>.run() at
/usr/local/lib/python3.8/dist-packages/twisted/internet/asyncioreactor.py:287>
Traceback (most recent call last):
File "/usr/lib/python3.8/asyncio/events.py", line 81, in _run
self._context.run(self._callback, *self._args)
File
"/usr/local/lib/python3.8/dist-packages/twisted/internet/asyncioreactor.py",
line 290, in run
f(*args, **kwargs)
File "/usr/local/lib/python3.8/dist-packages/daphne/server.py", line 295,
in application_checker
protocol.handle_exception(exception)
File "/usr/local/lib/python3.8/dist-packages/daphne/http_protocol.py",
line 301, in handle_exception
self.basic_error(500, b"Internal Server Error", "Exception inside
application.")
File "/usr/local/lib/python3.8/dist-packages/daphne/http_protocol.py",
line 342, in basic_error
self.handle_reply(
File "/usr/local/lib/python3.8/dist-packages/daphne/http_protocol.py",
line 242, in handle_reply
raise ValueError("HTTP response has already been started")
ValueError: HTTP response has already been started
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