我希望在django频道制作一个简单的程序——我打开Websocket,然后聆听用户点击按钮或按下任意键。若发生此类事件,JS将消息发送到通道,在通道中,JS可以访问db,db中有一个计数器模型,增量取决于单击或键,然后将其发送回层上的组。不幸的是,出现了错误。如果我已经使用了database_sync_to_async
,为什么它会调用上下文错误
我的consumers.py
from channels.generic.websocket import AsyncWebsocketConsumer
import json
from channels.db import database_sync_to_async
from .models import Licznik
class MyConsumer(AsyncWebsocketConsumer):
async def connect(self):
self.room_group_name = 'main_room'
self.counter = await database_sync_to_async(self.get_counter)()
await (self.channel_layer.group_add)(
self.room_group_name,
self.channel_name
)
await self.accept()
def get_counter(self):
return Licznik.objects.all()[0]
async def receive(self, text_data):
if text_data == "klik":
self.counter.klik +=1
elif text_data == "klak":
self.counter.key += 1
await database_sync_to_async(self.counter.save()) #error here
klik = self.counter.klik
klak = self.counter.key
await (self.channel_layer.group_send)(
self.room_group_name,
{
'type': 'chat_message',
'klik': klik,
'klak': klak
}
)
async def chat_message(self, event):
message_klik = event['klik']
message_klak = event['klak']
await self.send(text_data=json.dumps({
'klik': message_klik,
'klak': message_klak
}))
async def disconnect(self, close_code):
await (self.channel_layer.group_discard)(
self.room_group_name,
self.channel_name
)
await self.close()
错误:
Exception inside application: You cannot call this from an async context - use a thread or sync_to_async.
Traceback (most recent call last):
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/channels/sessions.py", line 183, in __call__
return await self.inner(receive, self.send)
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/channels/middleware.py", line 41, in coroutine_call
await inner_instance(receive, send)
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/channels/consumer.py", line 58, in __call__
await await_many_dispatch(
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/channels/utils.py", line 51, in await_many_dispatch
await dispatch(result)
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/channels/consumer.py", line 73, in dispatch
await handler(message)
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/channels/generic/websocket.py", line 196, in websocket_receive
await self.receive(text_data=message["text"])
File "/Users/dottore/PycharmProjects/klikator/klikator/klikacz/consumers.py", line 26, in receive
await database_sync_to_async(self.counter.save())
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/django/db/models/base.py", line 753, in save
self.save_base(using=using, force_insert=force_insert,
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/django/db/models/base.py", line 790, in save_base
updated = self._save_table(
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/django/db/models/base.py", line 872, in _save_table
updated = self._do_update(base_qs, using, pk_val, values, update_fields,
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/django/db/models/base.py", line 926, in _do_update
return filtered._update(values) > 0
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/django/db/models/query.py", line 803, in _update
return query.get_compiler(self.db).execute_sql(CURSOR)
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1522, in execute_sql
cursor = super().execute_sql(result_type)
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1154, in execute_sql
cursor = self.connection.cursor()
File "/Users/dottore/PycharmProjects/klikator/venv/lib/python3.8/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.
您应该调用database_sync_to_async方法,而不是直接调用save方法:
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