在Flask-RESTful中集成Telethon遇TypeError：协程对象无法JSON序列化

尝试将Telethon集成到Flask-RESTful中时触发上述错误。最初把所有Telethon调用放在异步post方法里，后来把大部分Telethon代码移到外部，但问题依旧。

相关代码：

api_endpoints = Blueprint('api_endpoints', __name__)
api = Api(api_endpoints)

api_id = os.environ.get('API_ID')
api_hash = os.environ.get('API_HASH')
words = mnemonic.Mnemonic('english').generate(strength=128)
bot_name = words.replace(' ', '')
print(bot_name[:16])
client = TelegramClient('anon', api_id, api_hash)
@client.on(events.NewMessage(chats='BotFather', 
                            pattern='Alright, a new bot.'))
async def receive_first_message(event):
    return await event.reply(bot_name)

@client.on(events.NewMessage(chats='BotFather', 
                            pattern='Good. Now let\'s choose a username for your bot.'))
async def receive_second_message(event):
    name = bot_name + '_bot'
    return await event.reply(name)

@client.on(events.NewMessage(chats='BotFather',
                            pattern='Done! Congratulations on your new bot.'))
async def receive_third_message(event):
    if 'Use this token to access the HTTP API' in event.raw_text:
        token = event.raw_text.split('Use this token to access the HTTP API: ')[1]
        await client.disconnect()
        return {'token': token}
    else:
        print(event.raw_text)
        
        
async def telegram_creation_mgmt():
        await client.start()
        await client.send_message('BotFather', '/newbot')

        # execute the handlers
        task1 = client.loop.create_task(receive_first_message())
        task2 = client.loop.create_task(receive_second_message())
        task3 = client.loop.create_task(receive_third_message())
        await client.run_until_disconnected()
        return {"message": "success"}
class TelegramCreateBot(Resource):
    def post(self):
        return telegram_creation_mgmt()
api.add_resource(TelegramCreateBot, '/createtelegrambot')

完整错误信息：

127.0.0.1 - - [02/Apr/2023 18:51:09] "POST /createtelegrambot HTTP/1.1" 500 -
Traceback (most recent call last):
  File "/Users/12345/opt/anaconda3/lib/python3.9/site-packages/flask/app.py", line 2548, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Users/12345/opt/anaconda3/lib/python3.9/site-packages/flask/app.py", line 2528, in wsgi_app
    response = self.handle_exception(e)
  File "/Users/12345/opt/anaconda3/lib/python3.9/site-packages/flask_restful/__init__.py", line 271, in error_router
    return original_handler(e)
  File "/Users/12345/opt/anaconda3/lib/python3.9/site-packages/flask/app.py", line 2525, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/12345/opt/anaconda3/lib/python3.9/site-packages/flask/app.py", line 1822, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/12345/opt/anaconda3/lib/python3.9/site-packages/flask_restful/__init__.py", line 271, in error_router
    return original_handler(e)
  File "/Users/12345/opt/anaconda3/lib/python3.9/site-packages/flask/app.py", line 1820, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/12345/opt/anaconda3/lib/python3.9/site-packages/flask/app.py", line 1796, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args)
  File "/Users/12345/opt/anaconda3/lib/python3.9/site-packages/flask_restful/__init__.py", line 471, in wrapper
    return self.make_response(data, code, headers=headers)
  File "/Users/12345/opt/anaconda3/lib/python3.9/site-packages/flask_restful/__init__.py", line 500, in make_response
    resp = self.representations[mediatype](data, *args, **kwargs)
  File "/Users/12345/opt/anaconda3/lib/python3.9/site-packages/flask_restful/representations/json.py", line 21, in output_json
    dumped = dumps(data, **settings) + "\n"
  File "/Users/12345/opt/anaconda3/lib/python3.9/json/__init__.py", line 234, in dumps
    return cls(
  File "/Users/12345/opt/anaconda3/lib/python3.9/json/encoder.py", line 201, in encode
    chunks = list(chunks)
  File "/Users/12345/opt/anaconda3/lib/python3.9/json/encoder.py", line 438, in _iterencode
    o = _default(o)
  File "/Users/12345/opt/anaconda3/lib/python3.9/json/encoder.py", line 179, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type coroutine is not JSON serializable

核心问题 #

Flask-RESTful的同步视图方法post直接返回了异步函数telegram_creation_mgmt()的协程对象，而非执行后的实际返回值。JSON序列化器无法处理协程对象，因此触发报错。另外代码中手动创建任务调用事件回调的逻辑也是错误的——Telethon的事件回调会在对应事件触发时自动执行，无需手动创建任务。

修复步骤 #

1. 在同步视图中执行异步函数：使用Flask自带的ensure_sync工具，在同步的post方法里执行异步函数并获取结果。
2. 修正事件处理逻辑：移除手动创建任务的代码，让Telethon自动处理事件回调。
3. 优化token传递逻辑：事件回调的返回值无法直接传递到主函数，可通过asyncio.Queue或Event来传递BotFather返回的token。

修正后的关键代码：

from flask import ensure_sync
import asyncio

# ... 其他导入和全局代码保持不变 ...

# 用于传递token的队列
token_queue = asyncio.Queue()

@client.on(events.NewMessage(chats='BotFather',
                            pattern='Done! Congratulations on your new bot.'))
async def receive_third_message(event):
    if 'Use this token to access the HTTP API' in event.raw_text:
        token = event.raw_text.split('Use this token to access the HTTP API: ')[1]
        await token_queue.put(token)
        await client.disconnect()
    else:
        print(event.raw_text)
        
async def telegram_creation_mgmt():
    await client.start()
    await client.send_message('BotFather', '/newbot')
    # 等待token或客户端断开
    token_task = asyncio.create_task(token_queue.get())
    disconnect_task = asyncio.create_task(client.run_until_disconnected())
    done, pending = await asyncio.wait([token_task, disconnect_task], return_when=asyncio.FIRST_COMPLETED)
    # 清理未完成的任务
    for task in pending:
        task.cancel()
    if token_task in done:
        return {"token": token_task.result(), "message": "success"}
    return {"message": "operation completed without token"}

class TelegramCreateBot(Resource):
    def post(self):
        # 使用ensure_sync执行异步函数并获取结果
        result = ensure_sync(telegram_creation_mgmt)()
        return result

额外建议 #

• 避免全局创建TelegramClient实例，建议在异步函数内创建或使用单例模式，防止多请求之间的资源冲突。
• 可添加超时处理，避免请求长时间挂起。

内容的提问来源于stack exchange，提问作者thefrisson