[FIXED] Issues with making a simple loading icon inside an async event loop

Issue

I'm making a bot for a discord server and have a function that takes a bit of time to run. I want to add a spinning loading icon next to the status message like this Doing something: <spinning icon>. It edits the original message to loop through these messages:

Doing something: \ Doing something: | Doing something: / Doing something: -

I tried using a separate thread to update the message like this:

async def loadingBar(ctx, message : discord.Message):

    loadingMessage0 = "{0}: \\".format(message)
    loadingMessage1 = "{0}: |".format(message)
    loadingMessage2 = "{0}: /".format(message)
    loadingMessage3 = "{0}: -".format(message)

    index = 0

    while True:
        if(index == 0):
            await message.edit(contents = loadingMessage0)
            index = 1
        elif(index == 1):
            await message.edit(contents = loadingMessage1)
            index = 2
        elif(index == 2):
            await message.edit(contents = loadingMessage2)
            index = 3
        elif(index == 1):
            await message.edit(contents = loadingMessage1)
            index = 0

farther down, the bot command that starts the process...

@bot.command()
async def downloadSong(ctx, url : str, songname : str):
    
    #Other code that doesn't matter

    message = await ctx.send("Downloading audio")

    _thread = threading.Thread(target=asyncio.run, args=(loadingBar(ctx, message),))
    _thread.start()

    #Function that takes a while

    #Some way to kill thread, never got this far

However, I get the error Task <Task pending coro=<loadingBar() running at bot.py:20> cb=[_run_until_complete_cb() at /Users/user/.pyenv/versions/3.7.3/lib/python3.7/asyncio/base_events.py:158]> got Future <Future pending> attached to a different loop. I'm new to async programming and the discord libraries; Is there a better way to do this and if not what am I doing wrong?

Solution

Firstly, you should add a delay between iterations inside the while loop, use asyncio.sleep for this.

Secondly - asyncio and threading doesn't really work together, there's also no point in using threading here since it defeats the whole purpose of asyncio, use asyncio.create_task to run the coroutine "in the background", you can asign it to a variable and then call the cancel method to stop the task.

import asyncio


async def loadingBar(ctx, message : discord.Message):
    loadingMessage0 = "{0}: \\".format(message)
    loadingMessage1 = "{0}: |".format(message)
    loadingMessage2 = "{0}: /".format(message)
    loadingMessage3 = "{0}: -".format(message)

    index = 0

    while True:
        if(index == 0):
            await message.edit(contents = loadingMessage0)
            index = 1
        elif(index == 1):
            await message.edit(contents = loadingMessage1)
            index = 2
        elif(index == 2):
            await message.edit(contents = loadingMessage2)
            index = 3
        elif(index == 1):
            await message.edit(contents = loadingMessage1)
            index = 0
        await asyncio.sleep(1)  # you can edit the message 5 times per 5 seconds


@bot.command()
async def downloadSong(ctx, url : str, songname : str):
    message = await ctx.send("Downloading audio")
    task = asyncio.create_task(loadingBar(ctx, message))  # starting the coroutine "in the background"

    # Function that takes a while

    task.cancel()  # stopping the background task

Answered By - Łukasz Kwieciński