discord.ext.tasks

在 1.1.0 版本加入.

One of the most common operations when making a bot is having a loop run in the background at a specified interval. This pattern is very common but has a lot of things you need to look out for:

• How do I handle asyncio.CancelledError?

• What do I do if the internet goes out?

• What is the maximum number of seconds I can sleep anyway?

The goal of this Pycord extension is to abstract all these worries away from you.

Recipes

A simple background task in a Cog:

from discord.ext import tasks, commands

class MyCog(commands.Cog):
    def __init__(self):
        self.index = 0
        self.printer.start()

    def cog_unload(self):
        self.printer.cancel()

    @tasks.loop(seconds=5.0)
    async def printer(self):
        print(self.index)
        self.index += 1

Adding an exception to handle during reconnect:

import asyncpg
from discord.ext import tasks, commands

class MyCog(commands.Cog):
    def __init__(self, bot):
        self.bot = bot
        self.data = []
        self.batch_update.add_exception_type(asyncpg.PostgresConnectionError)
        self.batch_update.start()

    def cog_unload(self):
        self.batch_update.cancel()

    @tasks.loop(minutes=5.0)
    async def batch_update(self):
        async with self.bot.pool.acquire() as con:
            # batch update here...
            pass

Looping a certain amount of times before exiting:

from discord.ext import tasks

@tasks.loop(seconds=5.0, count=5)
async def slow_count():
    print(slow_count.current_loop)

@slow_count.after_loop
async def after_slow_count():
    print('done!')

slow_count.start()

Waiting until the bot is ready before the loop starts:

from discord.ext import tasks, commands

class MyCog(commands.Cog):
    def __init__(self, bot):
        self.index = 0
        self.bot = bot
        self.printer.start()

    def cog_unload(self):
        self.printer.cancel()

    @tasks.loop(seconds=5.0)
    async def printer(self):
        print(self.index)
        self.index += 1

    @printer.before_loop
    async def before_printer(self):
        print('waiting...')
        await self.bot.wait_until_ready()

Doing something during cancellation:

from discord.ext import tasks, commands
import asyncio

class MyCog(commands.Cog):
    def __init__(self, bot):
        self.bot= bot
        self._batch = []
        self.lock = asyncio.Lock()
        self.bulker.start()

    async def do_bulk(self):
        # bulk insert data here
        ...

    @tasks.loop(seconds=10.0)
    async def bulker(self):
        async with self.lock:
            await self.do_bulk()

    @bulker.after_loop
    async def on_bulker_cancel(self):
        if self.bulker.is_being_cancelled() and len(self._batch) != 0:
            # if we're cancelled and we have some data left...
            # let's insert it to our database
            await self.do_bulk()

API Reference

Attributes

• current_loop
• hours
• minutes
• next_iteration
• seconds
• time

Methods

• async__call__
• defadd_exception_type
• @after_loop
• @before_loop
• defcancel
• defchange_interval
• defclear_exception_types
• @error
• deffailed
• defget_task
• defis_being_cancelled
• defis_running
• defremove_exception_type
• defrestart
• defstart
• defstop

class discord.ext.tasks.Loop(coro, seconds, hours, minutes, time, count, reconnect, loop, overlap)

A background task helper that abstracts the loop and reconnection logic for you.

The main interface to create this is through loop().

参数:

• coro (TypeVar(LF, bound= Callable[..., Awaitable[Any]]))

• seconds (float)

• hours (float)

• minutes (float)

• time (time | Sequence[time])

• count (int | None)

• reconnect (bool)

• loop (AbstractEventLoop)

• overlap (bool | int)

@after_loop(coro)

A decorator that register a coroutine to be called after the loop finished running.

The coroutine must take no arguments (except self in a class context).

备注

This coroutine is called even during cancellation. If it is desirable to tell apart whether something was cancelled or not, check to see whether is_being_cancelled() is True or not.

参数:

coro (TypeVar(FT, bound= Callable[..., Awaitable[Any]])) -- The coroutine to register after the loop finishes.

抛出:

TypeError -- The function was not a coroutine.

返回类型:

TypeVar(FT, bound= Callable[..., Awaitable[Any]])

@before_loop(coro)

A decorator that registers a coroutine to be called before the loop starts running.

This is useful if you want to wait for some bot state before the loop starts, such as discord.Client.wait_until_ready().

The coroutine must take no arguments (except self in a class context).

参数:

coro (TypeVar(FT, bound= Callable[..., Awaitable[Any]])) -- The coroutine to register before the loop runs.

抛出:

TypeError -- The function was not a coroutine.

返回类型:

TypeVar(FT, bound= Callable[..., Awaitable[Any]])

@error(coro)

A decorator that registers a coroutine to be called if the task encounters an unhandled exception.

The coroutine must take only one argument the exception raised (except self in a class context).

By default, this prints to sys.stderr however it could be overridden to have a different implementation.

在 1.4 版本加入.

参数:

coro (TypeVar(ET, bound= Callable[[Any, BaseException], Awaitable[Any]])) -- The coroutine to register in the event of an unhandled exception.

抛出:

TypeError -- The function was not a coroutine.

返回类型:

TypeVar(ET, bound= Callable[[Any, BaseException], Awaitable[Any]])

property seconds: float | None

Read-only value for the number of seconds between each iteration. None if an explicit time value was passed instead.

在 2.0 版本加入.

property minutes: float | None

Read-only value for the number of minutes between each iteration. None if an explicit time value was passed instead.

在 2.0 版本加入.

property hours: float | None

Read-only value for the number of hours between each iteration. None if an explicit time value was passed instead.

在 2.0 版本加入.

property time: list[time] | None

Read-only list for the exact times this loop runs at. None if relative times were passed instead.

在 2.0 版本加入.

property current_loop: int

The current iteration of the loop.

property next_iteration: datetime | None

When the next iteration of the loop will occur.

在 1.3 版本加入.

await __call__(*args, **kwargs)

This function is a coroutine.

Calls the internal callback that the task holds.

在 1.6 版本加入.

参数:

• *args (Any) -- The arguments to use.

• **kwargs (Any) -- The keyword arguments to use.

返回类型:

Any

start(*args, **kwargs)

Starts the internal task in the event loop.

参数:

• *args (Any) -- The arguments to use.

• **kwargs (Any) -- The keyword arguments to use.

抛出:

RuntimeError -- A task has already been launched and is running.

返回:

The task that has been created.

返回类型:

Task[None]

stop()

Gracefully stops the task from running.

Unlike cancel(), this allows the task to finish its current iteration before gracefully exiting.

备注

If the internal function raises an error that can be handled before finishing then it will retry until it succeeds.

If this is undesirable, either remove the error handling before stopping via clear_exception_types() or use cancel() instead.

在 1.2 版本加入.

返回类型:

None

cancel()

Cancels the internal task, if it is running.

返回类型:

None

restart(*args, **kwargs)

A convenience method to restart the internal task.

备注

Due to the way this function works, the task is not returned like start().

参数:

• *args (Any) -- The arguments to use.

• **kwargs (Any) -- The keyword arguments to use.

返回类型:

None

add_exception_type(*exceptions)

Adds exception types to be handled during the reconnect logic.

By default, the exception types handled are those handled by discord.Client.connect(), which includes a lot of internet disconnection errors.

This function is useful if you're interacting with a 3rd party library that raises its own set of exceptions.

参数:

*exceptions (type[BaseException]) -- An argument list of exception classes to handle.

抛出:

TypeError -- An exception passed is either not a class or not inherited from BaseException.

返回类型:

None

clear_exception_types()

Removes all exception types that are handled.

备注

This operation obviously cannot be undone!

返回类型:

None

remove_exception_type(*exceptions)

Removes exception types from being handled during the reconnect logic.

参数:

*exceptions (type[BaseException]) -- An argument list of exception classes to handle.

返回:

Whether all exceptions were successfully removed.

返回类型:

bool

get_task()

Fetches the internal task or None if there isn't one running.

返回类型:

Task[None] | None

is_being_cancelled()

Whether the task is being cancelled.

返回类型:

bool

failed()

Whether the internal task has failed.

在 1.2 版本加入.

返回类型:

bool

is_running()

Check if the task is currently running.

在 1.4 版本加入.

返回类型:

bool

change_interval(*, seconds=0, minutes=0, hours=0, time=...)

Changes the interval for the sleep time.

在 1.2 版本加入.

参数:

• seconds (float) -- The number of seconds between every iteration.

• minutes (float) -- The number of minutes between every iteration.

• hours (float) -- The number of hours between every iteration.

• time (time | Sequence[time]) --

  The exact times to run this loop at. Either a non-empty list or a single value of datetime.time should be passed. This cannot be used in conjunction with the relative time parameters.

  在 2.0 版本加入.

  备注

  Duplicate times will be ignored, and only run once.

抛出:

• ValueError -- An invalid value was given.

• TypeError -- An invalid value for the time parameter was passed, or the time parameter was passed in conjunction with relative time parameters.

返回类型:

None

discord.ext.tasks.loop(*, seconds=..., minutes=..., hours=..., time=..., count=None, reconnect=True, loop=..., overlap=False)

A decorator that schedules a task in the background for you with optional reconnect logic. The decorator returns a Loop.

参数:

• seconds (float) -- The number of seconds between every iteration.

• minutes (float) -- The number of minutes between every iteration.

• hours (float) -- The number of hours between every iteration.

• time (time | Sequence[time]) --

  The exact times to run this loop at. Either a non-empty list or a single value of datetime.time should be passed. Timezones are supported. If no timezone is given for the times, it is assumed to represent UTC time.

  This cannot be used in conjunction with the relative time parameters.

  备注

  Duplicate times will be ignored, and only run once.

  在 2.0 版本加入.

• count (int | None) -- The number of loops to do, None if it should be an infinite loop.

• reconnect (bool) -- Whether to handle errors and restart the task using an exponential back-off algorithm similar to the one used in discord.Client.connect().

• loop (AbstractEventLoop) -- The loop to use to register the task, if not given the default event loop is used via asyncio.get_event_loop() if it exists or one is created via asyncio.new_event_loop().

• overlap (bool | int) --

  Controls whether overlapping executions of the task loop are allowed. Set to False (default) to run iterations one at a time, True for unlimited overlap, or an int to cap the number of concurrent runs.

  在 2.7 版本加入.

抛出:

• ValueError -- An invalid value was given.

• TypeError -- The function was not a coroutine, an invalid value for the time parameter was passed, or time parameter was passed in conjunction with relative time parameters.

返回类型:

Callable[[TypeVar(LF, bound= Callable[..., Awaitable[Any]])], Loop[TypeVar(LF, bound= Callable[..., Awaitable[Any]])]]