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.. _discord_ext_tasks:
``discord.ext.tasks`` -- asyncio.Task helpers
====================================================
.. versionadded:: 1.1.0
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 :exc:`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 discord.py extension is to abstract all these worries away from you.
Recipes
---------
A simple background task in a :class:`~discord.ext.commands.Cog`:
.. code-block:: python3
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:
.. code-block:: python3
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:
.. code-block:: python3
from discord.ext import tasks
import discord
@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!')
class MyClient(discord.Client):
async def setup_hook(self):
slow_count.start()
Waiting until the bot is ready before the loop starts:
.. code-block:: python3
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:
.. code-block:: python3
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 cog_unload(self):
self.bulker.cancel()
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()
Doing something at a specific time each day:
.. code-block:: python3
import datetime
from discord.ext import commands, tasks
utc = datetime.timezone.utc
# If no tzinfo is given then UTC is assumed.
time = datetime.time(hour=8, minute=30, tzinfo=utc)
class MyCog(commands.Cog):
def __init__(self, bot):
self.bot = bot
self.my_task.start()
def cog_unload(self):
self.my_task.cancel()
@tasks.loop(time=time)
async def my_task(self):
print("My task is running!")
Doing something at multiple specific times each day:
.. code-block:: python3
import datetime
from discord.ext import commands, tasks
utc = datetime.timezone.utc
# If no tzinfo is given then UTC is assumed.
times = [
datetime.time(hour=8, tzinfo=utc),
datetime.time(hour=12, minute=30, tzinfo=utc),
datetime.time(hour=16, minute=40, second=30, tzinfo=utc)
]
class MyCog(commands.Cog):
def __init__(self, bot):
self.bot = bot
self.my_task.start()
def cog_unload(self):
self.my_task.cancel()
@tasks.loop(time=times)
async def my_task(self):
print("My task is running!")
.. _ext_tasks_api:
API Reference
---------------
.. attributetable:: discord.ext.tasks.Loop
.. autoclass:: discord.ext.tasks.Loop()
:members:
:special-members: __call__
:exclude-members: after_loop, before_loop, error
.. automethod:: Loop.after_loop()
:decorator:
.. automethod:: Loop.before_loop()
:decorator:
.. automethod:: Loop.error()
:decorator:
.. autofunction:: discord.ext.tasks.loop
:decorator:
|
