Discord.py Rewrite

Note : Before you start this tutorial, You should already know the language python, how to create applications in discord and you should've already invited the bot to your server.

Step 1 : Setting up

Create a new folder for your bot, it can be anything. For reference, I will name it Sample Bot.
Open up command prompt or terminal and type the following commands in it.
```
$ pip install -U discord.py
```
Now create a new file named main.py in your bot's folder. This file will hold the main bot.
Also create a new directory named cogs in your bot's directory, this will hold our command groups (aka cogs).
Now you're ready to code

Step 2 : The main bot

Open up your main.py file. Given below is some basic code with everything explained using comments.

from discord.ext import commands


def get_prefix(client, message):

    prefixes = ['=', '==']    # sets the prefixes, u can keep it as an array of only 1 item if you need only one prefix

    if not message.guild:
        prefixes = ['==']   # Only allow '==' as a prefix when in DMs, this is optional

    # Allow users to @mention the bot instead of using a prefix when using a command. Also optional
    # Do `return prefixes` if u don't want to allow mentions instead of prefix.
    return commands.when_mentioned_or(*prefixes)(client, message)


bot = commands.Bot(                         # Create a new bot
    command_prefix=get_prefix,              # Set the prefix
    description='A bot used for tutorial',  # Set a description for the bot
    owner_id=374886124126208000,            # Your unique User ID
    case_insensitive=True                   # Make the commands case insensitive
)

# case_insensitive=True is used as the commands are case sensitive by default


@bot.event
async def on_ready():                                       # Do this when the bot is logged in
    print(f'Logged in as {bot.user.name} - {bot.user.id}')  # Print the name and ID of the bot logged in.
    return

# Finally, login the bot
bot.run('BOT TOKEN here', bot=True, reconnect=True)

Now run this file, commands extension will prepare a default help command for you, you should see something similar to this when you use it: -
Note that it doesn't show help when =help is used as this was done in DMs, and we only allowed ==help in DMs.
Next we add the commands from the cogs directory.
Inside the cogs directory, create a new file named basic.py.
Add the following code above the
```
@bot.event
async def on_ready():
```
part in the main.py file
```
cogs = ['cogs.basic']
```
This basically points to the basic.py file in the cogs folder.

Next, change

async def on_ready():                                       
    print(f'Logged in as {bot.user.name} - {bot.user.id}')  
    return

async def on_ready():
    print(f'Logged in as {bot.user.name} - {bot.user.id}')
    for cog in cogs:
        bot.load_extension(cog)
    return

This will load the all the files specified in the cogs variable.

Next, open up the basic.py file and write the following code in it.

from discord.ext import commands
from datetime import datetime as d

# New - The Cog class must extend the commands.Cog class
class Basic(commands.Cog):
    
    def __init__(self, bot):
        self.bot = bot
        
    # Define a new command
    @commands.command(
        name='ping',
        description='The ping command',
        aliases=['p']
    )
    async def ping_command(self, ctx):
	    start = d.timestamp(d.now())
    	# Gets the timestamp when the command was used

    	msg = await ctx.send(content='Pinging')
    	# Sends a message to the user in the channel the message with the command was received.
    	# Notifies the user that pinging has started

    	await msg.edit(content=f'Pong!\nOne message round-trip took {( d.timestamp( d.now() ) - start ) * 1000 }ms.')
    	# Ping completed and round-trip duration show in ms
    	# Since it takes a while to send the messages
    	# it will calculate how much time it takes to edit an message.
    	# It depends usually on your internet connection speed
		return


def setup(bot):
    bot.add_cog(Basic(bot))
    # Adds the Basic commands to the bot
    # Note: The "setup" function has to be there in every cog file

This will add a new ping command to your bot!

Save the file

Step 3 : Checking the new command

Run the main.py again.
Use the help command. It should look something like this: -
Observe the new Basic category and ping command listed under it. This means that our command was successfully loaded.
Now use the help ping command, should look something like this: -
Note that in the example, it shows the prefix used by you!
Finally, let's use the ping command.
This is an example run (my internet is a bit slow)

Step 4 : Commands with arguments

Open up the basic.py file and add the following command to it by typing it just below the return statement of the ping command. This is a say command that repeats the words said by the user (in bold): -

	@commands.command(
        name='say',
        description='The say command',
        aliases=['repeat', 'parrot'],
        usage='<text>'
    )
    async def say_command(self, ctx):
        # The 'usage' only needs to show the parameters
        # As the rest of the format is generated automatically
        
        # Lets see what the parameters are: -
        # The self is just a regular reference to the class
        # ctx - is the Context related to the command
        # For more reference - https://discordpy.readthedocs.io/en/rewrite/ext/commands/api.html#context

        # Next we get the message with the command in it.
        msg = ctx.message.content

        # Extracting the text sent by the user
        # ctx.invoked_with gives the alias used
        # ctx.prefix gives the prefix used while invoking the command
        prefix_used = ctx.prefix
        alias_used = ctx.invoked_with
        text = msg[len(prefix_used) + len(alias_used):]
        
        # Next, we check if the user actually passed some text
        if text == '':
            # User didn't specify the text
            
            await ctx.send(content='You need to specify the text!')            

            pass
        else:
            # User specified the text.
            
            await ctx.send(content=f"**{text}**")
            
            pass

        return

Next, let's use this command!
As you can see, works perfectly!

Step 5 : Embeds

Since, we've already done this, let's do one final command. The embed command.
What this command will do?
- Ask for the title of the embed.
- Ask the user to specify the text for the embed description.
- Set a random color to the embed.
- Send the embed in the channel
What this will help you learn?
- How to create and send embeds.
- How to wait for user's response.
In your cogs directory, create a new file named embed.py
In your main.py file, to the cogs list which formerly was cogs = ['cogs.basic'] add a new cog i.e. 'cogs.embed', making it - cogs = ['cogs.basic', 'cogs.embed'] . This will tell it to also treat the embed.py file as another cog.
Open up the embed.py file and write the following code in it: -

from discord.ext import commands
import discord
import random

# These color constants are taken from discord.js library
colors = {
  'DEFAULT': 0x000000,
  'WHITE': 0xFFFFFF,
  'AQUA': 0x1ABC9C,
  'GREEN': 0x2ECC71,
  'BLUE': 0x3498DB,
  'PURPLE': 0x9B59B6,
  'LUMINOUS_VIVID_PINK': 0xE91E63,
  'GOLD': 0xF1C40F,
  'ORANGE': 0xE67E22,
  'RED': 0xE74C3C,
  'GREY': 0x95A5A6,
  'NAVY': 0x34495E,
  'DARK_AQUA': 0x11806A,
  'DARK_GREEN': 0x1F8B4C,
  'DARK_BLUE': 0x206694,
  'DARK_PURPLE': 0x71368A,
  'DARK_VIVID_PINK': 0xAD1457,
  'DARK_GOLD': 0xC27C0E,
  'DARK_ORANGE': 0xA84300,
  'DARK_RED': 0x992D22,
  'DARK_GREY': 0x979C9F,
  'DARKER_GREY': 0x7F8C8D,
  'LIGHT_GREY': 0xBCC0C0,
  'DARK_NAVY': 0x2C3E50,
  'BLURPLE': 0x7289DA,
  'GREYPLE': 0x99AAB5,
  'DARK_BUT_NOT_BLACK': 0x2C2F33,
  'NOT_QUITE_BLACK': 0x23272A
}


class Embed(commands.Cog):

    def __init__(self, bot):
        self.bot = bot

    @commands.command(
        name='embed',
        description='The embed command',
    )
    async def embed_command(self, ctx):

        # Define a check function that validates the message received by the bot
        def check(ms):
            # Look for the message sent in the same channel where the command was used
            # As well as by the user who used the command.
            return ms.channel == ctx.message.channel and ms.author == ctx.message.author

        # First ask the user for the title
        await ctx.send(content='What would you like the title to be?')

        # Wait for a response and get the title
        msg = await self.bot.wait_for('message', check=check)
        title = msg.content # Set the title

        # Next, ask for the content
        await ctx.send(content='What would you like the Description to be?')
        msg = await self.bot.wait_for('message', check=check)
        desc = msg.content

        # Finally make the embed and send it
        msg = await ctx.send(content='Now generating the embed...')

        color_list = [c for c in colors.values()]
        # Convert the colors into a list
        # To be able to use random.choice on it

        embed = discord.Embed(
            title=title,
            description=desc,
            color=random.choice(color_list)
        )
        # Also set the thumbnail to be the bot's pfp
        embed.set_thumbnail(url=self.bot.user.avatar_url)

        # Also set the embed author to the command user
        embed.set_author(
            name=ctx.message.author.name,
            icon_url=ctx.message.author.avatar_url
        )

        await msg.edit(
            embed=embed,
            content=None
        )
        # Editing the message
        # We have to specify the content to be 'None' here
        # Since we don't want it to stay to 'Now generating embed...'

        return


def setup(bot):
    bot.add_cog(Embed(bot))
    # Adds the Basic commands to the bot
    # Note: The "setup" function has to be there in every cog file

Now, let's run this command!
And that's it!

Step 6 : Changing the default help command

As we've already seen, commands extension already comes with a built-in help command. Let's use it again!
Pretty clearly, it's very ugly. So, let's change it!
So, what we'll do is, remove the pre-defined help command and then create a new help command in the embed.py file.

Open up the main.py file and make the following changes: -

@bot.event
async def on_ready():
    print(f'Logged in as {bot.user.name} - {bot.user.id}')
    bot.remove_command('help')
    # Removes the help command
    # Make sure to do this before loading the cogs
    for cog in cogs:
        bot.load_extension(cog)
    return

Open the embed.py file and make a new help command is given below: -

NOTE : We're making this in the embed.py file because this help command will be using embeds too. ( though it's not necessary to do even if it uses embeds, I just don't want to create another file with all those colors).

What this help command will do?

Get all the cogs registered.
If the user has passed a cog argument,
then list all commands under that cog.

Else, list all cogs and commands under them.

@commands.command(
   name='help',
   description='The help command!',
   aliases=['commands', 'command'],
   usage='cog'
)
async def help_command(self, ctx, cog='all'):
   
   # The third parameter comes into play when
   # only one word argument has to be passed by the user

   # Prepare the embed

   color_list = [c for c in colors.values()]
   help_embed = discord.Embed(
       title='Help',
       color=random.choice(color_list)
   )
   help_embed.set_thumbnail(url=self.bot.user.avatar_url)
   help_embed.set_footer(
       text=f'Requested by {ctx.message.author.name}',
       icon_url=self.bot.user.avatar_url
   )

   # Get a list of all cogs
   cogs = [c for c in self.bot.cogs.keys()]

   # If cog is not specified by the user, we list all cogs and commands

   if cog == 'all':
       for cog in cogs:
           # Get a list of all commands under each cog

           cog_commands = self.bot.get_cog(cog).get_commands()
           commands_list = ''
           for comm in cog_commands:
               commands_list += f'**{comm.name}** - *{comm.description}*\n'

           # Add the cog's details to the embed.

           help_embed.add_field(
               name=cog,
               value=commands_list,
               inline=False
           ).add_field(
               name='\u200b', value='\u200b', inline=False
           )

           # Also added a blank field '\u200b' is a whitespace character.
       pass
   else:

       # If the cog was specified

       lower_cogs = [c.lower() for c in cogs]

       # If the cog actually exists.
       if cog.lower() in lower_cogs:

           # Get a list of all commands in the specified cog
           commands_list = self.bot.get_cog(cogs[ lower_cogs.index(cog.lower()) ]).get_commands()
           help_text=''

           # Add details of each command to the help text
           # Command Name
           # Description
           # [Aliases]
           #
           # Format
           for command in commands_list:
               help_text += f'```{command.name}```\n' \
                   f'**{command.description}**\n\n'

               # Also add aliases, if there are any
               if len(command.aliases) > 0:
                   help_text += f'**Aliases :** `{"`, `".join(command.aliases)}`\n\n\n'
               else:
                   # Add a newline character to keep it pretty
                   # That IS the whole purpose of custom help
                   help_text += '\n'

               # Finally the format
               help_text += f'Format: `@{self.bot.user.name}#{self.bot.user.discriminator}' \
                   f' {command.name} {command.usage if command.usage is not None else ""}`\n\n\n\n'

           help_embed.description = help_text
       else:
           # Notify the user of invalid cog and finish the command
           await ctx.send('Invalid cog specified.\nUse `help` command to list all cogs.')
           return

   await ctx.send(embed=help_embed)
   
   return

This is just an example and gives you an basic idea of what it is like. Below is a sample run of this new help command.
No cog specified, commands listed
Embed cog specified, show the details of commands under Embed category.
Invalid cog specified, send error message.

Quick Tip

Use .env files to store your token. I've used .env file to store my token in the final code. You can learn more about how to use .env files here.

The End

Those are all the basics you'll need to know, refer to API Reference for reference on the discord.py commands extension. You can also refer to the main library docs. All of the above code can be obtained at here. Also you can visit this link to learn how to host your discord bots on repl.it!

@AkimotoRyou Thanks for the patience, I have updated both my tutorial and the final example to match the latest requirements. Thanks for informing me.