小编Ale*_*cer的帖子

我有一个 django 2 应用程序，我使用 django 通道进行套接字连接。

我只是将 django 更新到版本 3。现在当我尝试建立套接字连接时，daphne 显示此错误。我对 django 2 没有任何问题。

[Failure instance: Traceback: <class 'django.core.exceptions.SynchronousOnlyOperation'>: You cannot call this from an async context - use a thread or sync_to_async.
/home/ubuntu/pl_env/lib/python3.6/site-packages/autobahn/websocket/protocol.py:2844:processHandshake
/home/ubuntu/pl_env/lib/python3.6/site-packages/txaio/tx.py:429:as_future
/home/ubuntu/pl_env/lib/python3.6/site-packages/twisted/internet/defer.py:151:maybeDeferred
/home/ubuntu/pl_env/lib/python3.6/site-packages/daphne/ws_protocol.py:83:onConnect
--- <exception caught here> ---
/home/ubuntu/pl_env/lib/python3.6/site-packages/twisted/internet/defer.py:151:maybeDeferred
/home/ubuntu/pl_env/lib/python3.6/site-packages/daphne/server.py:201:create_application
/home/ubuntu/pl_env/lib/python3.6/site-packages/channels/routing.py:54:__call__
/home/ubuntu/pl_env/lib/python3.6/site-packages/channels/security/websocket.py:37:__call__
/home/ubuntu/petroline_django/orders/token_auth.py:25:__call__
/home/ubuntu/pl_env/lib/python3.6/site-packages/django/db/models/manager.py:82:manager_method
/home/ubuntu/pl_env/lib/python3.6/site-packages/django/db/models/query.py:411:get
/home/ubuntu/pl_env/lib/python3.6/site-packages/django/db/models/query.py:258:__len__
/home/ubuntu/pl_env/lib/python3.6/site-packages/django/db/models/query.py:1261:_fetch_all
/home/ubuntu/pl_env/lib/python3.6/site-packages/django/db/models/query.py:57:__iter__
/home/ubuntu/pl_env/lib/python3.6/site-packages/django/db/models/sql/compiler.py:1142:execute_sql
/home/ubuntu/pl_env/lib/python3.6/site-packages/django/utils/asyncio.py:24:inner

它说问题出在 token_auth.py，第 25 行。这一行是 token = Token.objects.get(key=token_key)

这是我处理令牌认证的 token_auth.py。

from channels.auth import AuthMiddlewareStack
from django.contrib.auth.models import AnonymousUser
from django.db import close_old_connections
from rest_framework.authtoken.models import Token


class …

我在我的项目中使用了 postgresql 数据库，我使用了 django文档中的以下示例。

from django.db.models import OuterRef, Subquery
newest = Comment.objects.filter(post=OuterRef('pk')).order_by('-created_at')
Post.objects.annotate(newest_commenter_email=Subquery(newest.values('email')[:1]))

但不是最新的评论者电子邮件，我需要最后两封评论者的电子邮件。我改变了[:1]对[:2]，但此异常引发：ProgrammingError: more than one row returned by a subquery used as an expression。