Not subscribing to specific Intents may break discord.js functionality

[monbrey]

Documenting this here so people can reference this is future PRs.

With Discord providing supports for bots to subscribe to the type of events they want to receive via Intents, this can have some unintended impacts on how discord.js works.

Most noticeably, since Discord.js assumes all Guilds and GuildChannels will be cached (as per current functionality) omitting the GUILDS intent breaks things.

Example code, with issue present:

const client = new Discord.Client({
    partials: ["REACTION", "MESSAGE"],
    ws: { intents: ["GUILD_MESSAGES"] }
});

client.on("message", message => {
    console.log(message.content);
});
client.on("raw", console.log);

In this example, the raw event emits a MESSAGE_CREATE with full message, author and member data.

{
    type: 0,
    tts: false,
    timestamp: '2020-03-10T03:47:47.743000+00:00',
    pinned: false,
    nonce: '686782331209383936',
    mentions: [],
    mention_roles: [],
    mention_everyone: false,
    member: {
      roles: [Array],
      premium_since: null,
      nick: null,
      mute: false,
      joined_at: '2018-02-11T06:18:41.269000+00:00',
      hoisted_role: null,
      deaf: false
    },
    id: '686782331981529107',
    flags: 0,
    embeds: [],
    edited_timestamp: null,
    content: 'test',
    channel_id: '620798312160821280',
    author: {
      username: 'Monbrey',
      id: '122157285790187530',
      discriminator: '4502',
      avatar: '42fd1742230b86f138d323bf20e369d5'
    },
    attachments: [],
    guild_id: '412130302958239745'
}

The data includes guild_id and channel_id, which could be used to fetch a Guild and GuildChannel via the respective Managers. However client.on("message") doesn't emit at all, not even a Partial. It relies on a channel existing in cache for anything to be emitted: see https://github.com/discordjs/discord.js/blob/36050d07f5ded196f5f6601619da2d3dc3604126/src/client/actions/MessageCreate.js#L7-L36

Fixed:

const client = new Discord.Client({
    partials: ["REACTION", "MESSAGE"],
    ws: { intents: ["GUILDS", "GUILD_MESSAGES"] }
});

client.on("message", message => {
    console.log(message.content);
});

Adding the GUILDS intent allows the bot to receive the full Guilds and Channels expected in the identify payload, and cache everything. Events will then emit as expected.

To properly support a partial implementation of this where Guild and Channel could be uncached, the Message class would need to switch to the guildID/channelID property approach, with getters for the object, in the same way member properties like <Guild>.ownerID are handled.

[Fyko]

Do you think a set of default intents would be a good idea? They could apply when a ClientOptions#ws#intents is not supplied and perhaps throw some sort of warning?

[monbrey]

Do you think a set of default intents would be a good idea?

I can go either way on that. I think there's some value in forcing people to define the ones they need, as that's in line with why Discord is introducing them.

If we set a default, it should probably be all non-privileged intents, but we could also just advise that as an easy way to do it in the guide.

[advaith1]

imo:

• we should document the intent(s) needed on all events and properties
• we shouldn't set default intents, there are too many people who don't know what intents are ask about the checkboxes when they're going through verification, and it helps with resource usage
• we should allow setting intents right in ClientOptions to make it more friendly/discoverable (ws and http are more lower-level)
• we should include intents in examples and as part of making a bot in the guide