Good practices

Running code when a cog is loaded

Most people are used to running everything in __init__ but that doesn't allow running async code. In this case you can overwrite the special cog_load method.

class MyCog(commands.Cog):
    def __init__(self, bot: commands.Bot):
        self.bot = bot

    async def cog_load(self):
        self.data = await bot.fetch_database_data()

    @commands.slash_command()
    async def command(self, interaction: disnake.ApplicationCommandInteraction, user: disnake.User):
        await interaction.response.send_message(self.data[user.id])

Reloading your bot

One of the lesser known disnake features is the reload kwarg for your bot. It reloads extensions every time they are edited; allowing you to test your code in real-time. This is especially useful if startup times for your bot are very slow, since only one extension will be reloaded at a time.

from disnake.ext import commands

bot = commands.Bot(..., reload=True)

caution

This should be used purely for debugging. Please do not use this in production.

Converting arguments in commands

discord.py used to have Converter classes to convert arguments if they are provided. These were however very hard to use with type-checkers because the type of the parameter is never actually the converter itself.

Disnake aims to eliminate this issue by only allowing conversion of builtin types like disnake.Member, disnake.Emoji, etc. If you ever want to have your own converter you have to use the converter argument in Param.

disnake

async def convert_data(inter: disnake.ApplicationCommandInteraction, arg: str):
    parts = arg.split(",")
    return {"a": parts[0], "b": int(parts[1]), "c": parts[2].lower()}


@commands.slash_command()
async def command(
    self,
    inter: disnake.ApplicationCommandInteraction,
    data: Dict[str, Any] = commands.Param(converter=convert_data),
):
    ...

discord.py

class DataConverter(commands.Converter):
    async def convert(self, ctx: commands.Context, arg: str):
        parts = arg.split(",")
        return {"a": parts[0], "b": int(parts[1]), "c": parts[2].lower()}


@commands.command()
async def command(self, ctx: commands.Context, data: DataConverter):
    ...

If you absolutely want to be able to use classes you may pass in a class method. Alternatively, set a method of the class to be the converter using converter_method.

classmethod converter

from dataclasses import dataclass


@dataclass
class Data:
    a: str
    b: int

    @classmethod
    async def from_option(cls, inter: disnake.CommandInteraction, arg: str):
        a, b = arg.split(",")
        return cls(a, int(b))


@commands.slash_command()
async def command(
    self,
    inter: disnake.CommandInteraction,
    data: Data = commands.Param(converter=Data.from_option),
):
    ...

converter method

from dataclasses import dataclass


@dataclass
class Data:
    a: str
    b: int

    @commands.converter_method
    async def from_option(cls, inter: disnake.CommandInteraction, arg: str):
        a, b = arg.split(",")
        return cls(a, int(b))


@commands.slash_command()
async def command(
    self,
    inter: disnake.CommandInteraction,
    data: Data,
):
    ...

Context command targets

Instead of using inter.target you should be using a parameter of your command.

@commands.user_command()
async def command(self, inter: disnake.ApplicationCommandInteraction, user: disnake.User):
    await inter.response.send_message(f"Used on {user.mention}")

Slash command descriptions

You may use docstrings for command and option descriptions. Everything before Parameters is the command description. Everything after Parameters are the option descriptions.

@commands.slash_command()
async def command(
    self,
    inter: disnake.ApplicationCommandInteraction,
    category: str,
    item: str,
    details: bool,
):
    """Show item info

    Parameters
    ----------
    category: The category to search
    item: The item to display
    details: Whether to get the details of this time
    """

Guild-only commands

While disnake does provide a @commands.guild_only() decorator, it still makes you handle guild being optional in case you're using linters. To solve this you should be using GuildCommandInteraction.

# before
@commands.slash_command()
@commands.guild_only()
async def command(inter: disnake.ApplicationCommandInteraction):
    assert inter.guild is not None
    await inter.send(inter.guild.name)


# after
@commands.slash_command()
async def command(inter: disnake.GuildCommandInteraction):
    await inter.send(inter.guild.name)