Raise custom error message for

Question

So below code blocks server and user id in the list when they use ?hello, so I am trying to raise custom error message. If user id is in list, it will tell User Blacklisted and if server id is in list, it will tell Server has been Blacklisted.

LIST_OF_USER_IDS = ['34534545546', '34534545546']
LIST_OF_SERVER_IDS = ['34534545546', '34534545546']

def blacklists(users, servers):
    def predicate(ctx):
        return ctx.message.author.id not in users and ctx.message.server.id not in servers
    return commands.check(predicate)

@bot.command(pass_context=True)
@blacklists(LIST_OF_USER_IDS, LIST_OF_SERVER_IDS)
async def hello(ctx):
     await bot.say("Hello {}".format(ctx.message.author.mention))

So I tried below code but getting error. I'm just a beginner so my code is not correct, so I need a help to fix this.

def blacklists(users, servers):
    def predicate(ctx):
        return ctx.message.author.id not in users and ctx.message.server.id not in servers
    return commands.check(predicate)
try:
       if ctx.message.author.id in LIST_OF_USER_IDS:
           raise UserBlacklisted
       elif ctx.message.server.id in LIST_OF_SERVER_IDS:
           raise ServerBlacklisted
       break
   except UserBlacklisted:
       await bot.send_message(ctx.message.channel, "User Blacklisted")
   except ServerBlacklisted:
       await bot.send_message(ctx.message.channel, "Server has been Blacklisted")

Answer 1

Instead of returning False if the check fails, instead raise a subclass of CommandError, then handle that error in the on_command_error event.

class UserBlacklisted(commands.CommandError):
    def __init__(self, user, *args, **kwargs):
        self.user = user
        super().__init__(*args, **kwargs)

class ServerBlacklisted(commands.CommandError):
    def __init__(self, server, *args, **kwargs):
        self.server = server
        super().__init__(*args, **kwargs)


def blacklists(users, servers):
    def predicate(ctx):
        if ctx.message.author.id in users:
            raise UserBlacklisted(ctx.message.author)
        elif ctx.message.server.id in servers:
            raise ServerBlacklisted(ctx.message.server)
        else:
            return True
    return commands.check(predicate)

@bot.event
async def on_command_error(error, ctx):
    if isinstance(error, UserBlacklisted):
        await bot.send_message(ctx.message.channel, "User {} has been blacklisted".format(error.user.mention))
    elif isinstance(error, ServerBlacklisted):
        await bot.send_message(ctx.message.channel, "Server {} has been blacklisted".format(error.server.name))



@bot.command(pass_context=True)
@blacklists(LIST_OF_USER_IDS, LIST_OF_SERVER_IDS)
async def hello(ctx):
     await bot.say("Hello {}".format(ctx.message.author.mention))