ARTICLES

Discord: creating a bot

By adam

April 9, 2020

Creating a bot on discord

While there are some samples in discord.py. The API is fairly flat and hard to navigate.

Here are the links to getting started:

Understanding the context

The Context (ctx) is often the first argument in the functions from @bot.command. This ctx contains most of the things needed to identify the message triggering the robot to respond (ctx fields):

guild - on which server the robot was triggered
message - the message of the command
author - the author of the message
send() - a function that allows the robot to respond back as a response to the trigger

From this it is obvious you need some other way of getting at the channel where the message was sent. Fortunately many of the things you need are actually included in ctx.message.

In particular, ctx.message.channel points to the originating channel.

But if you wanted to get a list of all the channels in the server you would be looking at them in ctx.guild.channels, and you could also get all the members of the server with ctx.guild.members, or if looking for a particular user use ctx.guild.get_member_named(), which allows you to find by name or name#discriminator where the discriminator is a 4 digit number.

Webhook

It is possible to create webhooks from a particular channel, this webhook is essential in that it allows a send() inclusing a username and avatar_url. This comes in handy when moving a message from one channel to another channel.

Message

Given a messageId, it is possible to fetch a message in a particular channel. There are a few fields that are particularly useful:

content
author
embeds
attachments
created_at
edited_at

Mention

The string in the message content that signifies a mention has the following format:

<@!{author.id}>

This can be compared with the usual tag which is

{author.name}#{author.discriminator}

Note that author.mention doesn’t contain the exclamation mark.

Avatar

The avatars are stored in a cdn and can be obtained from author.avatar_url

Python types

Union and Optional type hints.

stackoverflow

full implementation

import discord
from discord.ext import commands
import random


description = """An example bot"""
bot=commands.Bot(command_prefix='?', description=description)

@bot.event
async def on_ready():
    print("We have logged in as {0.name} {0.id}".format(bot.user))

@bot.command()
async def roll(ctx, dice: str):
    try:
        rolls, limit = map(int, dice.split('d'))
    except Exception:
        await ctx.send('Format has to be in NdN!')
        return
    result = ", ".join(str(random.randint(1,limit)) for r in range(rolls))
    await ctx.send(result)

@bot.command()
async def mv(ctx, messageId, toChannelName, *kargs):
    # Transform some of the kargs
    opts = dict()
    for x in kargs:
        if x.find('=') != -1:
            k,v = x.split('=')
            opts[k] = v

    # get the channel from where the message originated
    print("Guild:", ctx.guild.name,
          ", Channel:", ctx.message.channel.name,
          ", Command: mv")

    # fromChannel
    fromChannel = ctx.message.channel

    # finds the destination channel and gets a webhook
    tChan = [x for x in ctx.guild.channels if x.name == toChannelName]
    if len(tChan) == 0: return
    toChannel = tChan[0]
    wbs = await toChannel.webhooks()
    if len(wbs) < 1:
        wb = await toChannel.create_webhook(name='Move message')
    else:
        wb = wbs[0]

    # gets the original message
    message = await fromChannel.fetch_message(messageId)

    print("Moving message...")
    print("Author: {0.name} {0.discriminator} {0.id} {0.mention} {0.avatar_url}".format(message.author))
    print("Embeds:", message.embeds)
    print("Attachments:", message.attachments)
    print("Content:", message.content)

    # Used to assign a different author using the from= option
    author = message.author
    if 'from' in opts:
        fauthor = ctx.guild.get_member_named(opts['from'])
        if fauthor is not None:
            print("Setting author to {0.name}.".format(fauthor))
            author = fauthor

    # Create a header for message being moved
    mention = "From <@!{}>, ".format(author.id)
    if message.edited_at:
        msgtime = "edited at {}.\n\n".format(message.edited_at)
    else:
        msgtime = "created at {}.\n\n".format(message.created_at)
    tag = "{0.name}#{0.discriminator}".format(author)

    # Sending to other channel
    await wb.send(content=mention+msgtime+message.content,
                  username=tag,
                  avatar_url=author.avatar_url,
                  tts=False,
                  embeds=message.embeds,
                  files=message.attachments)

bot.run(bot_token)

discord
bot