Python调用telegram.ext.JobQueue报context缺失错误的解决方法

我计划在代码中使用telegram.ext.JobQueue实现每30秒执行一次news()函数，该函数会通过Telegram为我发送document（文档），初始代码如下：

def start(update: Update, context: CallbackContext):
    update.message.reply_text(
        "Hello, Welcome to my Bot. Please write /help to see the commands available.")
    context.job_queue.run_repeating(news, interval=30, first=10, context=update.message.chat_id)

def news(update: Update, context: CallbackContext):

    s = io.StringIO()
    csv.writer(s).writerows(newlist)
    s.seek(0)
    buf = io.BytesIO()
    buf.write(s.getvalue().encode())
    buf.seek(0)
    buf.name = f'items.csv'
    context.bot.send_document(chat_id=update.message.chat_id, document=buf)

触发错误的代码行：

context.job_queue.run_repeating(news, interval=30, first=10, context=update.message.chat_id)

在Telegram bot中触发/start指令时得到如下报错：

No error handlers are registered, logging exception.
Traceback (most recent call last):
  File "/Users/arman/anaconda3/lib/python3.8/site-packages/telegram/ext/dispatcher.py", line 555, in process_update
    handler.handle_update(update, self, check, context)
  File "/Users/arman/anaconda3/lib/python3.8/site-packages/telegram/ext/handler.py", line 198, in handle_update
    return self.callback(update, context)
  File "/Users/arman/Downloads/test3.py", line 23, in start
    context.job_queue.run_repeating(news, interval=10, first=10, context=update.message.chat_id)
  File "/Users/arman/anaconda3/lib/python3.8/site-packages/telegram/ext/jobqueue.py", line 293, in run_repeating
    j = self.scheduler.add_job(
  File "/Users/arman/anaconda3/lib/python3.8/site-packages/apscheduler/schedulers/base.py", line 434, in add_job
    job = Job(self, **job_kwargs)
  File "/Users/arman/anaconda3/lib/python3.8/site-packages/apscheduler/job.py", line 49, in __init__
    self._modify(id=id or uuid4().hex, **kwargs)
  File "/Users/arman/anaconda3/lib/python3.8/site-packages/apscheduler/job.py", line 180, in _modify
    check_callable_args(func, args, kwargs)
  File "/Users/arman/anaconda3/lib/python3.8/site-packages/apscheduler/util.py", line 401, in check_callable_args
    raise ValueError('The following arguments have not been supplied: %s' %
ValueError: The following arguments have not been supplied: context

报错核心是news函数的签名不符合JobQueue定时回调的规范：

• 响应用户消息/指令的回调，需要接收(update, context)两个入参，这类回调由用户发送的Update事件触发，能拿到对应的update对象
• JobQueue触发的定时任务回调只接收一个context: CallbackContext类型的参数——定时任务是调度器到点自动执行，没有对应的用户触发事件，根本不存在update参数。你通过run_repeating的context参数传入的chat_id，会挂载在context.job.context属性上供回调使用。

你给news定义了两个入参，调度器执行时只会传入一个context对象，参数数量不匹配，就抛出了缺参数的错误。

修改news函数的签名和内部取值逻辑即可，start函数里的run_repeating调用不需要改动，你传context=update.message.chat_id的写法是正确的：

def news(context: CallbackContext):
    # 从job.context中取出之前传入的chat_id
    chat_id = context.job.context
    s = io.StringIO()
    csv.writer(s).writerows(newlist)
    s.seek(0)
    buf = io.BytesIO()
    buf.write(s.getvalue().encode())
    buf.seek(0)
    buf.name = f'items.csv'
    context.bot.send_document(chat_id=chat_id, document=buf)

补充说明：如果你用的是python-telegram-bot v20+异步版本，回调需要加async关键字，调用发送消息方法时要加await，从你贴的报错路径判断当前用的是v13.x同步版本，不需要做这部分调整。

内容的提问来源于stack exchange，提问作者user13622589