Cannot instantiate async_to_sync inside a SyncConsumer method

I’m getting this error from the worker (BTBitstampTrades). Any clue?

I think is because I’m defining the callback function inside the Worker method.

How could I send something to the channel layer from inside the callback def?

error from callback <bound method Connection._on_message of <Connection(Thread-1, started daemon 140206694061824)>>: You cannot instantiate AsyncToSync inside a thread that wasn’t made using SyncToAsync

My code:

class WsTradeHistory(JsonWebsocketConsumer):
    def connect(self):
        self.accept()
        async_to_sync(self.channel_layer.group_add)("users", self.channel_name)
        print('USUARIO CONECTADO' + self.channel_name)

    def disconnect(self, code):
        async_to_sync(self.channel_layer.group_discard)("users", self.channel_name)

    def receive_json(self, content, **kwargs):
        if content['group_request']:
            group_req = content['group_request']
            async_to_sync(self.channel_layer.group_add)(group_req, self.channel_name)
            if group_req == 'th_bitstamp_BTC_USD':
                print('BITSTAMP TRADES!')
                # self.bitstamp_trades('')
                async_to_sync(self.channel_layer.send)(
                    "bitstamp_trades",
                    {
                        "type": "get.data",
                    }
                )

    def trade_data(self, event):
        print('Enviando trade data al Usuario')
        self.send_json(json.loads(event["text"]))

    def one_trade(self, event):
        self.send_json(json.loads(event["text"]))

class BTBitstampTrades(SyncConsumer):

    def get_data(self, event):
        print('START WORKER')

        def callback(*args, **kwargs):
            async_to_sync(self.channel_layer.send)(
                "th_bitstamp_BTC_USD",
                {
                    "type": "one.trade",
                    "text": args[0]
                }
            )

        # We can't subscribe until we've connected, so we use a callback handler
        # to subscribe when able
        def connect_handler(data):
            channel = pusher.subscribe('live_trades')
            channel.bind('trade', callback)

        pusher = pysher.Pusher('de504dc5763aeef9ff52')
        pusher.connection.bind('pusher:connection_established', connect_handler)
        pusher.connect()

Ubuntu 16.04, Google Chrome, Django y Channels 2.02, Python 3.6

[andrewgodwin]

I just advise that you upgrade packages you’re finding issues in before reporting an issue. It’s a bit confusing for Channels as we have four - asgiref, daphne, channels and channels_redis.

[hishnash]

No, i don think it is to do with it being inside a nested def but rather that callback is called by pysher.Pusher and that is happing after def get_data(self, event): has completed (your get_data method is automaticly wrapped in a SyncToAsync)

try:

def callback(*args, **kwargs):
    if getattr(SyncToAsync.threadlocal, "main_event_loop", None) is None:
        loop = asyncio.get_event_loop()
        loop.run_until_complete(
            self.channel_layer.send(
                "th_bitstamp_BTC_USD",
                {
                    "type": "one.trade",
                    "text": args[0]
                }
            )
        )
        loop.close()
    else:
        async_to_sync(self.channel_layer.send)(
            "th_bitstamp_BTC_USD",
            {
                "type": "one.trade",
                "text": args[0]
            }
        )