在 discord.py 中，我有一个清除/清除消息命令。 我希望它在执行该命令时显示特定消息

Question

I have set the command permissions to be manage_messages. meaning, a person with manage messages permissions can only execute that command. but when a person without that permission uses it, i want it to display a custom message, like 'You cannot do that.' or something.

here is my whole code.

import os
import discord
from discord.ext import commands
import random


bot = commands.Bot(command_prefix = '-')


my_token = os.environ['Token']


@bot.event
async def on_ready():
  print('Bot is Ready')


#errors
@bot.event
async def on_command_error(ctx, error):
  if isinstance(error,commands.MissingRequiredArgument):
    await ctx.send('Please enter all the required Arguments')


#help cmd
bot.remove_command('help')
@bot.group(invoke_without_command=True)
async def help(ctx):
  em1 = discord.Embed(
        title = 'Help',
        description = 'Commands to get you started!'
        )
  em1.add_field(name = '8ball', value = 'random answers')
  await ctx.send(embed = em1)


#ping latency....
@bot.command()
async def ping(ctx):
  await ctx.send(f'Pong {round(bot.latency * 1000)}ms')

#8ball
@bot.command(aliases=['8ball', '8b'])
async def _8ball(ctx, *, question,):
  responses = ['It is Certain.',
              'It is decidedly so.',
              'Without a doubt.',
              'Yes definitely.',
              'You may rely on it.',
              'As I see it, yes.',
              'Most likely.',
              'Outlook good.',
              'Yes.',
              'Signs point to yes.',
              'Reply hazy, try again.',
              'Ask again later.',
              'Better not tell you now.',
              'Cannot predict now.']
  await ctx.send(f'Question: {question} Answer: {random.choice(responses)}')


#clear
@bot.command()
@commands.has_permissions(manage_messages = True)
async def clear(ctx, amount=0):
  await ctx.channel.purge(limit=amount)


keep_alive.keep_alive()
bot.run(my_token)```

Answer 1

@commands.has_permissions raises commands.MissingPermissions error if user has no permission to use.

async def on_command_error(ctx, error):
    if isinstance(error, commands.MissingRequiredArgument):
        await ctx.send('Please enter all the required Arguments')
    elif isinstance(error, commands.MissingPermissions):
        await ctx.send("You are not allowed to do that.")

Answer 2

You can use permissions_in method like that:

@bot.command()
async def clear(ctx, amount=0):
    if ctx.author.permissions_in(ctx.channel).manage_messages:
        await ctx.channel.purge(limit=amount)
    else:
        await ctx.send("You don't have permissions to do that")

This:

ctx.author.permissions_in(ctx.channel).manage_messages

will check wether the author of the message have permissions to manage messages in the channel that the message was sent in, if the author have the permission it will return True otherwise it will return False .