Django 3.0 + 频道 + ASGI + TokenAuthMiddleware答案

【问题标题】：Django 3.0 + Channels + ASGI + TokenAuthMiddlewareDjango 3.0 + 频道 + ASGI + TokenAuthMiddleware
【发布时间】：2020-01-31 18:20:23
【问题描述】：

我升级到 Django 3.0，现在使用 websockets + TokenAuthMiddleware 时出现此错误：

SynchronousOnlyOperation
You cannot call this from an async context - use a thread or sync_to_async.

【问题讨论】：

标签： django django-channels asgi

【解决方案1】：

问题是您无法从异步上下文访问同步代码。这是 Django 3.0 的TokenAuthMiddleware：

# myproject.myapi.utils.py
from channels.auth import AuthMiddlewareStack
from channels.db import database_sync_to_async
from django.contrib.auth.models import AnonymousUser

from rest_framework.authtoken.models import Token


@database_sync_to_async
def get_user(headers):
    try:
        token_name, token_key = headers[b'authorization'].decode().split()
        if token_name == 'Token':
            token = Token.objects.get(key=token_key)
            return token.user
    except Token.DoesNotExist:
        return AnonymousUser()


class TokenAuthMiddleware:

    def __init__(self, inner):
        self.inner = inner

    def __call__(self, scope):
        return TokenAuthMiddlewareInstance(scope, self)


class TokenAuthMiddlewareInstance:
    """
    Yeah, this is black magic:
    https://github.com/django/channels/issues/1399
    """
    def __init__(self, scope, middleware):
        self.middleware = middleware
        self.scope = dict(scope)
        self.inner = self.middleware.inner

    async def __call__(self, receive, send):
        headers = dict(self.scope['headers'])
        if b'authorization' in headers:
            self.scope['user'] = await get_user(headers)
        inner = self.inner(self.scope)
        return await inner(receive, send)


TokenAuthMiddlewareStack = lambda inner: TokenAuthMiddleware(AuthMiddlewareStack(inner))

像这样使用它：

# myproject/routing.py
from myapi.utils import TokenAuthMiddlewareStack
from myapi.websockets import WSAPIConsumer

application = ProtocolTypeRouter({
    "websocket": TokenAuthMiddlewareStack(
        URLRouter([
            path("api/v1/ws", WSAPIConsumer),
        ]),
    ),

})
application = SentryAsgiMiddleware(application)

【讨论】：

请将此标记为答案。完美无瑕！如果我以前发现这个，我就不会浪费时间了。
它不再起作用了：TypeError: __call__() missing 2 required positional arguments: 'receive' and 'send'

【解决方案2】：

作为@tapion stated，这个解决方案不再适用，因为channels 3.x

新的解决方案可以稍微调整一下：

class TokenAuthMiddleware:
    def __init__(self, inner):
        self.inner = inner

    async def __call__(self, scope, receive, send):
        headers = dict(scope['headers'])
        if b'authorization' in headers:
            scope['user'] = await get_user(headers)
        return await self.inner(scope, receive, send)

【讨论】：