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How to call async method which get event loop in main thread inside another async method in Quart?

t.py

from telethon import TelegramClient, functions, types client2 = TelegramClient(sn, api_id, api_hash).start() async def create_contact(): return await client2(functions.contacts.ImportContactsRequest([ types.InputPhoneContact(0, '8', 'first_name', 'last_name') ]))

app.py

from quart import Quart, websocket,render_template,request import t2 app = Quart(__name__) @app.route('/wa2tg') def wa2tg(): return render_template('wa2tg.html',nm=request.args.get('nm','')) @app.websocket('/wa2tg2') async def wa2tg2(): while True: data = await websocket.receive() await t2.create_contact() # Thread(target=tele.client2.run_until_disconnected).start() app.run(debug=1)

Error:

Running on http://127.0.0.1:5000 (CTRL + C to quit) [2019-06-21 16:31:42,035] 127.0.0.1:51696 GET /wa2tg 1.1 200 553 12995 [2019-06-21 16:31:42,486] 127.0.0.1:51698 GET /wa2tg2 1.1 101 - 999 [2019-06-21 16:31:42,490] ERROR in app: Exception on websocket /wa2tg2 Traceback (most recent call last): File "C:\Users\Smart\AppData\Local\Programs\Python\Python37-32\lib\site-packages\quart\app.py", line 1629, in handle_websocket return await self.full_dispatch_websocket(websocket_context) File "C:\Users\Smart\AppData\Local\Programs\Python\Python37-32\lib\site-packages\quart\app.py", line 1651, in full_dispatch_websocket result = await self.handle_user_exception(error) File "C:\Users\Smart\AppData\Local\Programs\Python\Python37-32\lib\site-packages\quart\app.py", line 948, in handle_user_exception raise error File "C:\Users\Smart\AppData\Local\Programs\Python\Python37-32\lib\site-packages\quart\app.py", line 1649, in full_dispatch_websocket result = await self.dispatch_websocket(websocket_context) File "C:\Users\Smart\AppData\Local\Programs\Python\Python37-32\lib\site-packages\quart\app.py", line 1694, in dispatch_websocket return await handler(**websocket_.view_args) File "D:\SmartBot\my_env\SmartBot\t.py", line 13, in wa2tg2 await t2.create_contact() File "D:\SmartBot\my_env\SmartBot\t2.py", line 22, in create_contact types.InputPhoneContact(0, '8807328487', 'first_name', 'last_name') File "C:\Users\Smart\AppData\Local\Programs\Python\Python37-32\lib\site-packages\telethon\client\users.py", line 60, in __call__ result = await future RuntimeError: Task <Task pending coro=<ASGIWebsocketConnection.handle_websocket() running at C:\Users\Smart\AppData\Local\Programs\Python\Python37-32\lib\site-packages\quart\asgi.py:135> cb=[_wait.<locals>._on_completion() at C:\Users\Smart\AppData\Local\Programs\Python\Python37-32\lib\asyncio\tasks.py:440]> got Future <Future pending> attached to a different loop

How to pass event loop to quart? I tried to get the loop and set inside function but still got error

loop = asyncio.get_event_loop() @app.websocket('/wa2tg2') async def wa2tg2(): while True: asyncio.set_event_loop(loop) data = await websocket.receive() await t2.create_contact()
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  • By editing your question to change your code after receiving answers, you make it much less useful to people with similar problems who find this question when looking for help. Commented Dec 23, 2021 at 18:41

3 Answers 3

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When you do:

TelegramClient(sn, api_id, api_hash)

Telethon needs to asyncio.get_event_loop(). This method returns the event loop for the current thread, which in your code, is the main thread. Telethon then remembers and uses the loop from the main thread.

When you do:

Thread(target=tele.client2.run_until_disconnected).start()

You are creating a new thread, and you get the corresponding error "Task got Future attached to a different loop" for the reasons I have explained.

When using asyncio, you generally shouldn't use threading unless you really know what you're doing.

In fact, the code can be rewritten as (removing all the unnecessary imports which probably were added without much thought):

Tele.py

from telethon import TelegramClient, functions, types client = TelegramClient(sn, api_id, api_hash).start() async def create_contact(): return await client2(functions.contacts.ImportContactsRequest([ types.InputPhoneContact(0, phone_number, first_name, last_name) ]))

app.py

from quart import Quart, websocket app = Quart(__name__) @app.websocket('/wa2tg2') async def wa2tg2(): while True: data = await websocket.receive() await tele.create_contact()

Some things to note:

  • client.start() can work without await.
  • client.run_until_disconnected() only needs to be called if you need to.
  • async def are called by using await on them, not by creating a separate thread.
  • The 0 you use in input contact will only work once (or not at all), since it needs to be a random number.
  • Never copy paste blindly. Understand what it does first.
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3 Comments

Error raised in function only. Threading works fine. But I commented out threading and still the same error
The 0 you use in input contact will only work once (or not at all), since it needs to be a random number. works fine
Official applications use random numbers, and we have had issues with it in the past.
0

Solved after passing loop to app.run

loop = asyncio.get_event_loop() app.run(debug=1,loop=loop)

Thread for client.run_until_disconnected() not needed since we pass the loop to the run method

More on Telethon and Quart

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It actually happens because Uvicorn tends to instantiate its own event loop.

In a nutshell, put your FastAPI app instantiation and the Uvicorn invocation in two separate files. This will resolve the issue.

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