Partials (#3070)

* Remove GroupDMChannels

they sparked no joy

* Start partials for message deletion

* MessageUpdate partials

* Add partials as an opt-in client option

* Add fetch() to Message

* Message.author should never be undefined

* Fix channels being the wrong type

* Allow fetching channels

* Refactor and add reaction add partials

* Reaction remove partials

* Check for emoji first

* fix message fetching

janky

* User partials in audit logs

* refactor overwrite code

* guild member partials

* partials as a whitelist

* document GuildMember#fetch

* fix: check whether a structure is a partial, not whether cache is true

* typings: Updated for latest commit (#3075)

* partials: fix messageUpdate behaviour (now "old" message can be partial)

* partials: add warnings and docs

* partials: add partials to index.yml

* partials: tighten "partial" definitions

* partials: fix embed-only messages counting as partials

docs/index.yml

@@ -12,6 +12,8 @@
       path: voice.md
     - name: Web builds
       path: web.md
+    - name: Partials
+      path: partials.md
 - name: Examples
   files:
     - name: Ping

docs/topics/partials.md

@@ -0,0 +1,61 @@
+# Partials
+
+Partials allow you to receive events that contain uncached instances, providing structures that contain very minimal
+data. For example, if you were to receive a `messageDelete` event with an uncached message, normally Discord.js would
+discard the event. With partials, you're able to receive the event, with a Message object that contains just an ID.
+
+## Opting in
+
+Partials are opt-in, and you can enable them in the Client options by specifying [PartialTypes](../typedef/PartialType):
+
+```js
+// Accept partial messages and DM channels when emitting events
+new Client({ partials: ['MESSAGE', 'CHANNEL'] });
+```
+
+## Usage & warnings
+
+<warn>The only guaranteed data a partial structure can store is its ID. All other properties/methods should be
+considered invalid/defunct while accessing a partial structure.</warn>
+
+After opting-in with the above, you begin to allow partial messages and channels in your caches, so it's important
+to check whether they're safe to access whenever you encounter them, whether it be in events or through normal cache
+usage.
+
+All instance of structures that you opted-in for will have a `partial` property. As you'd expect, this value is `true`
+when the instance is partial. Partial structures are only guaranteed to contain an ID, any other properties and methods
+no longer carry their normal type guarantees.
+
+This means you have to take time to consider possible parts of your program that might need checks put in place to
+prevent accessing partial data:
+
+```js
+client.on('messageDelete', message => {
+  console.log(`${message.id} was deleted!`);
+  // Partial messages do not contain any content so skip them
+  if (!message.partial) {
+    console.log(`It had content: "${message.content}"`);
+  }
+})
+
+// You can also try to upgrade partials to full instances:
+client.on('messageReactionAdd', async (reaction, user) => {
+  // If a message gains a reaction and it is uncached, fetch and cache the message
+  // You should account for any errors while fetching, it could return API errors if the resource is missing
+  if (reaction.message.partial) await reaction.message.fetch();
+  // Now the message has been cached and is fully available:
+  console.log(`${reaction.message.author}'s message "${reaction.message.content}" gained a reaction!`);
+});
+```
+
+<info>If a message is deleted and both the message and channel are uncached, you must enable both 'MESSAGE' and
+'CHANNEL' in the client options to receive the messageDelete event.</info>
+
+## Why?
+
+This allows developers to listen to events that contain uncached data, which is useful if you're running a moderation
+bot or any bot that relies on still receiving updates to resources you don't have cached -- message reactions are a
+good example.
+
+Currently, the only type of channel that can be uncached is a DM channel, there is no reason why guild channels should
+not be cached.

src/client/Client.js

@@ -434,6 +434,9 @@ class Client extends BaseClient {
     if (typeof options.disableEveryone !== 'boolean') {
       throw new TypeError('CLIENT_INVALID_OPTION', 'disableEveryone', 'a boolean');
     }
+    if (!(options.partials instanceof Array)) {
+      throw new TypeError('CLIENT_INVALID_OPTION', 'partials', 'an Array');
+    }
     if (typeof options.restWsBridgeTimeout !== 'number' || isNaN(options.restWsBridgeTimeout)) {
       throw new TypeError('CLIENT_INVALID_OPTION', 'restWsBridgeTimeout', 'a number');
     }

src/client/actions/Action.js

@@ -1,5 +1,7 @@
 'use strict';
 
+const { PartialTypes } = require('../../util/Constants');
+
 /*
 
 ABOUT ACTIONS
@@ -20,6 +22,27 @@ class GenericAction {
   handle(data) {
     return data;
   }
+
+  getChannel(data) {
+    const id = data.channel_id || data.id;
+    return data.channel || (this.client.options.partials.includes(PartialTypes.CHANNEL) ?
+      this.client.channels.add({
+        id,
+        guild_id: data.guild_id,
+      }) :
+      this.client.channels.get(id));
+  }
+
+  getMessage(data, channel) {
+    const id = data.message_id || data.id;
+    return data.message || (this.client.options.partials.includes(PartialTypes.MESSAGE) ?
+      channel.messages.add({
+        id,
+        channel_id: channel.id,
+        guild_id: data.guild_id || (channel.guild ? channel.guild.id : null),
+      }) :
+      channel.messages.get(id));
+  }
 }
 
 module.exports = GenericAction;

src/client/actions/ChannelCreate.js

@@ -12,7 +12,7 @@ class ChannelCreateAction extends Action {
       /**
        * Emitted whenever a channel is created.
        * @event Client#channelCreate
-       * @param {DMChannel|GroupDMChannel|GuildChannel} channel The channel that was created
+       * @param {DMChannel|GuildChannel} channel The channel that was created
        */
       client.emit(Events.CHANNEL_CREATE, channel);
     }

src/client/actions/ChannelDelete.js

@@ -19,7 +19,7 @@ class ChannelDeleteAction extends Action {
       /**
        * Emitted whenever a channel is deleted.
        * @event Client#channelDelete
-       * @param {DMChannel|GroupDMChannel|GuildChannel} channel The channel that was deleted
+       * @param {DMChannel|GuildChannel} channel The channel that was deleted
        */
       client.emit(Events.CHANNEL_DELETE, channel);
     }

src/client/actions/MessageDelete.js

@@ -6,11 +6,10 @@ const { Events } = require('../../util/Constants');
 class MessageDeleteAction extends Action {
   handle(data) {
     const client = this.client;
-    const channel = client.channels.get(data.channel_id);
+    const channel = this.getChannel(data);
     let message;
-
     if (channel) {
-      message = channel.messages.get(data.id);
+      message = this.getMessage(data, channel);
       if (message) {
         channel.messages.delete(message.id);
         message.deleted = true;

src/client/actions/MessageReactionAdd.js

@@ -11,15 +11,19 @@ const Action = require('./Action');
 
 class MessageReactionAdd extends Action {
   handle(data) {
+    if (!data.emoji) return false;
+
     const user = data.user || this.client.users.get(data.user_id);
     if (!user) return false;
+
     // Verify channel
-    const channel = data.channel || this.client.channels.get(data.channel_id);
+    const channel = this.getChannel(data);
     if (!channel || channel.type === 'voice') return false;
+
     // Verify message
-    const message = data.message || channel.messages.get(data.message_id);
+    const message = this.getMessage(data, channel);
     if (!message) return false;
-    if (!data.emoji) return false;
+
     // Verify reaction
     const reaction = message.reactions.add({
       emoji: data.emoji,

src/client/actions/MessageReactionRemove.js

@@ -12,15 +12,19 @@ const { Events } = require('../../util/Constants');
 
 class MessageReactionRemove extends Action {
   handle(data) {
+    if (!data.emoji) return false;
+
     const user = this.client.users.get(data.user_id);
     if (!user) return false;
+
     // Verify channel
-    const channel = this.client.channels.get(data.channel_id);
+    const channel = this.getChannel(data);
     if (!channel || channel.type === 'voice') return false;
+
     // Verify message
-    const message = channel.messages.get(data.message_id);
+    const message = this.getMessage(data, channel);
     if (!message) return false;
-    if (!data.emoji) return false;
+
     // Verify reaction
     const emojiID = data.emoji.id || decodeURIComponent(data.emoji.name);
     const reaction = message.reactions.get(emojiID);

src/client/actions/MessageReactionRemoveAll.js

@@ -5,10 +5,12 @@ const { Events } = require('../../util/Constants');
 
 class MessageReactionRemoveAll extends Action {
   handle(data) {
-    const channel = this.client.channels.get(data.channel_id);
+    // Verify channel
+    const channel = this.getChannel(data);
     if (!channel || channel.type === 'voice') return false;
 
-    const message = channel.messages.get(data.message_id);
+    // Verify message
+    const message = this.getMessage(data, channel);
     if (!message) return false;
 
     message.reactions.clear();

src/client/actions/MessageUpdate.js

@@ -4,11 +4,10 @@ const Action = require('./Action');
 
 class MessageUpdateAction extends Action {
   handle(data) {
-    const client = this.client;
+    const channel = this.getChannel(data);
-
-    const channel = client.channels.get(data.channel_id);
     if (channel) {
-      const message = channel.messages.get(data.id);
+      const { id, channel_id, guild_id, author, timestamp, type } = data;
+      const message = this.getMessage({ id, channel_id, guild_id, author, timestamp, type }, channel);
       if (message) {
         message.patch(data);
         return {

src/client/websocket/handlers/CHANNEL_PINS_UPDATE.js

@@ -14,7 +14,7 @@ module.exports = (client, { d: data }) => {
      * Emitted whenever the pins of a channel are updated. Due to the nature of the WebSocket event,
      * not much information can be provided easily here - you need to manually check the pins yourself.
      * @event Client#channelPinsUpdate
-     * @param {DMChannel|GroupDMChannel|TextChannel} channel The channel that the pins update occured in
+     * @param {DMChannel|TextChannel} channel The channel that the pins update occured in
      * @param {Date} time The time of the pins update
      */
     client.emit(Events.CHANNEL_PINS_UPDATE, channel, time);

src/client/websocket/handlers/CHANNEL_UPDATE.js

@@ -8,8 +8,8 @@ module.exports = (client, packet) => {
     /**
      * Emitted whenever a channel is updated - e.g. name change, topic change.
      * @event Client#channelUpdate
-     * @param {DMChannel|GroupDMChannel|GuildChannel} oldChannel The channel before the update
+     * @param {DMChannel|GuildChannel} oldChannel The channel before the update
-     * @param {DMChannel|GroupDMChannel|GuildChannel} newChannel The channel after the update
+     * @param {DMChannel|GuildChannel} newChannel The channel after the update
      */
     client.emit(Events.CHANNEL_UPDATE, old, updated);
   }

src/index.js

@@ -65,7 +65,6 @@ module.exports = {
   Collector: require('./structures/interfaces/Collector'),
   DMChannel: require('./structures/DMChannel'),
   Emoji: require('./structures/Emoji'),
-  GroupDMChannel: require('./structures/GroupDMChannel'),
   Guild: require('./structures/Guild'),
   GuildAuditLogs: require('./structures/GuildAuditLogs'),
   GuildChannel: require('./structures/GuildChannel'),

src/stores/ChannelStore.js

@@ -5,7 +5,7 @@ const Channel = require('../structures/Channel');
 const { Events } = require('../util/Constants');
 
 const kLru = Symbol('LRU');
-const lruable = ['group', 'dm'];
+const lruable = ['dm'];
 
 /**
  * Stores channels.
@@ -54,6 +54,7 @@ class ChannelStore extends DataStore {
 
   add(data, guild, cache = true) {
     const existing = this.get(data.id);
+    if (existing && existing.partial && cache) existing._patch(data);
     if (existing) return existing;
 
     const channel = Channel.create(this.client, data, guild);
@@ -85,11 +86,12 @@ class ChannelStore extends DataStore {
    *   .then(channel => console.log(channel.name))
    *   .catch(console.error);
    */
-  fetch(id, cache = true) {
+  async fetch(id, cache = true) {
     const existing = this.get(id);
-    if (existing) return Promise.resolve(existing);
+    if (existing && !existing.partial) return existing;
 
-    return this.client.api.channels(id).get().then(data => this.add(data, null, cache));
+    const data = await this.client.api.channels(id).get();
+    return this.add(data, null, cache);
   }
 
   /**

src/stores/DataStore.js

@@ -18,6 +18,7 @@ class DataStore extends Collection {
 
   add(data, cache = true, { id, extras = [] } = {}) {
     const existing = this.get(id || data.id);
+    if (existing && existing.partial && cache && existing._patch) existing._patch(data);
     if (existing) return existing;
 
     const entry = this.holds ? new this.holds(this.client, data, ...extras) : data;

src/stores/GuildMemberStore.js

@@ -180,7 +180,7 @@ class GuildMemberStore extends DataStore {
 
   _fetchSingle({ user, cache }) {
     const existing = this.get(user);
-    if (existing && existing.joinedTimestamp) return Promise.resolve(existing);
+    if (existing && !existing.partial) return Promise.resolve(existing);
     return this.client.api.guilds(this.guild.id).members(user).get()
       .then(data => this.add(data, cache));
   }

src/stores/MessageStore.js

@@ -40,6 +40,7 @@ class MessageStore extends DataStore {
    * <info>The returned Collection does not contain reaction users of the messages if they were not cached.
    * Those need to be fetched separately in such a case.</info>
    * @param {Snowflake|ChannelLogsQueryOptions} [message] The ID of the message to fetch, or query parameters.
+   * @param {boolean} [cache=true] Whether to cache the message(s)
    * @returns {Promise<Message>|Promise<Collection<Snowflake, Message>>}
    * @example
    * // Get message
@@ -57,8 +58,8 @@ class MessageStore extends DataStore {
    *   .then(messages => console.log(`${messages.filter(m => m.author.id === '84484653687267328').size} messages`))
    *   .catch(console.error);
    */
-  fetch(message) {
+  fetch(message, cache = true) {
-    return typeof message === 'string' ? this._fetchId(message) : this._fetchMany(message);
+    return typeof message === 'string' ? this._fetchId(message, cache) : this._fetchMany(message, cache);
   }
 
   /**
@@ -80,15 +81,17 @@ class MessageStore extends DataStore {
     });
   }
 
-  async _fetchId(messageID) {
+  async _fetchId(messageID, cache) {
+    const existing = this.get(messageID);
+    if (existing && !existing.partial) return existing;
     const data = await this.client.api.channels[this.channel.id].messages[messageID].get();
-    return this.add(data);
+    return this.add(data, cache);
   }
 
-  async _fetchMany(options = {}) {
+  async _fetchMany(options = {}, cache) {
     const data = await this.client.api.channels[this.channel.id].messages.get({ query: options });
     const messages = new Collection();
-    for (const message of data) messages.set(message.id, this.add(message));
+    for (const message of data) messages.set(message.id, this.add(message, cache));
     return messages;
   }
 

src/stores/UserStore.js

@@ -51,11 +51,11 @@ class UserStore extends DataStore {
    * @param {boolean} [cache=true] Whether to cache the new user object if it isn't already
    * @returns {Promise<User>}
    */
-  fetch(id, cache = true) {
+  async fetch(id, cache = true) {
     const existing = this.get(id);
-    if (existing) return Promise.resolve(existing);
+    if (existing && !existing.partial) return existing;
-
+    const data = await this.client.api.users(id).get();
-    return this.client.api.users(id).get().then(data => this.add(data, cache));
+    return this.add(data, cache);
   }
 }
 

src/structures/APIMessage.js

@@ -330,7 +330,7 @@ module.exports = APIMessage;
 
 /**
  * A target for a message.
- * @typedef {TextChannel|DMChannel|GroupDMChannel|User|GuildMember|Webhook|WebhookClient} MessageTarget
+ * @typedef {TextChannel|DMChannel|User|GuildMember|Webhook|WebhookClient} MessageTarget
  */
 
 /**

src/structures/Channel.js

@@ -16,7 +16,6 @@ class Channel extends Base {
     /**
      * The type of the channel, either:
      * * `dm` - a DM channel
-     * * `group` - a Group DM channel
      * * `text` - a guild text channel
      * * `voice` - a guild voice channel
      * * `category` - a guild category channel
@@ -84,15 +83,20 @@ class Channel extends Base {
     return this.client.api.channels(this.id).delete().then(() => this);
   }
 
+  /**
+   * Fetches this channel.
+   * @returns {Promise<Channel>}
+   */
+  fetch() {
+    return this.client.channels.fetch(this.id, true);
+  }
+
   static create(client, data, guild) {
     const Structures = require('../util/Structures');
     let channel;
-    if (data.type === ChannelTypes.DM) {
+    if (data.type === ChannelTypes.DM || (data.type !== ChannelTypes.GROUP && !data.guild_id && !guild)) {
       const DMChannel = Structures.get('DMChannel');
       channel = new DMChannel(client, data);
-    } else if (data.type === ChannelTypes.GROUP) {
-      const GroupDMChannel = Structures.get('GroupDMChannel');
-      channel = new GroupDMChannel(client, data);
     } else {
       guild = guild || client.guilds.get(data.guild_id);
       if (guild) {

src/structures/ClientUser.js

@@ -164,42 +164,6 @@ class ClientUser extends Structures.get('User') {
   setAFK(afk) {
     return this.setPresence({ afk });
   }
-
-  /**
-   * An object containing either a user or access token, and an optional nickname.
-   * @typedef {Object} GroupDMRecipientOptions
-   * @property {UserResolvable} [user] User to add to the Group DM
-   * @property {string} [accessToken] Access token to use to add a user to the Group DM
-   * (only available if a bot is creating the DM)
-   * @property {string} [nick] Permanent nickname (only available if a bot is creating the DM)
-   * @property {string} [id] If no user resolvable is provided and you want to assign nicknames
-   * you must provide user ids instead
-   */
-
-  /**
-   * Creates a Group DM.
-   * @param {GroupDMRecipientOptions[]} recipients The recipients
-   * @returns {Promise<GroupDMChannel>}
-   * @example
-   * // Create a Group DM with a token provided from OAuth
-   * client.user.createGroupDM([{
-   *   user: '66564597481480192',
-   *   accessToken: token
-   * }])
-   *   .then(console.log)
-   *   .catch(console.error);
-   */
-  createGroupDM(recipients) {
-    const data = this.bot ? {
-      access_tokens: recipients.map(u => u.accessToken),
-      nicks: recipients.reduce((o, r) => {
-        if (r.nick) o[r.user ? r.user.id : r.id] = r.nick;
-        return o;
-      }, {}),
-    } : { recipients: recipients.map(u => this.client.users.resolveID(u.user || u.id)) };
-    return this.client.api.users('@me').channels.post({ data })
-      .then(res => this.client.channels.add(res));
-  }
 }
 
 module.exports = ClientUser;

src/structures/DMChannel.js

@@ -12,6 +12,8 @@ const MessageStore = require('../stores/MessageStore');
 class DMChannel extends Channel {
   constructor(client, data) {
     super(client, data);
+    // Override the channel type so partials have a known type
+    this.type = 'dm';
     /**
      * A collection containing the messages sent to this channel
      * @type {MessageStore<Snowflake, Message>}
@@ -23,11 +25,13 @@ class DMChannel extends Channel {
   _patch(data) {
     super._patch(data);
 
-    /**
+    if (data.recipients) {
-     * The recipient on the other end of the DM
+      /**
-     * @type {User}
+       * The recipient on the other end of the DM
-     */
+       * @type {User}
-    this.recipient = this.client.users.add(data.recipients[0]);
+       */
+      this.recipient = this.client.users.add(data.recipients[0]);
+    }
 
     /**
      * The ID of the last message in the channel, if one was sent
@@ -42,6 +46,14 @@ class DMChannel extends Channel {
     this.lastPinTimestamp = data.last_pin_timestamp ? new Date(data.last_pin_timestamp).getTime() : null;
   }
 
+  /**
+   * Whether this DMChannel is a partial
+   * @type {boolean}
+   */
+  get partial() {
+    return !this.recipient;
+  }
+
   /**
    * When concatenated with a string, this automatically returns the recipient's mention instead of the
    * DMChannel object.

src/structures/GroupDMChannel.js

@@ -1,245 +0,0 @@
-'use strict';
-
-const Channel = require('./Channel');
-const TextBasedChannel = require('./interfaces/TextBasedChannel');
-const Collection = require('../util/Collection');
-const DataResolver = require('../util/DataResolver');
-const MessageStore = require('../stores/MessageStore');
-
-/*
-{ type: 3,
-  recipients:
-   [ { username: 'Charlie',
-       id: '123',
-       discriminator: '6631',
-       avatar: '123' },
-     { username: 'Ben',
-       id: '123',
-       discriminator: '2055',
-       avatar: '123' },
-     { username: 'Adam',
-       id: '123',
-       discriminator: '2406',
-       avatar: '123' } ],
-  owner_id: '123',
-  name: null,
-  last_message_id: '123',
-  id: '123',
-  icon: null }
-*/
-
-/**
- * Represents a Group DM on Discord.
- * @extends {Channel}
- * @implements {TextBasedChannel}
- */
-class GroupDMChannel extends Channel {
-  constructor(client, data) {
-    super(client, data);
-    /**
-     * A collection containing the messages sent to this channel
-     * @type {MessageStore<Snowflake, Message>}
-     */
-    this.messages = new MessageStore(this);
-    this._typing = new Map();
-  }
-
-  _patch(data) {
-    super._patch(data);
-
-    /**
-     * The name of this Group DM, can be null if one isn't set
-     * @type {string}
-     */
-    this.name = data.name;
-
-    /**
-     * A hash of this Group DM icon
-     * @type {?string}
-     */
-    this.icon = data.icon;
-
-    /**
-     * The user ID of this Group DM's owner
-     * @type {Snowflake}
-     */
-    this.ownerID = data.owner_id;
-
-    /**
-     * If the DM is managed by an application
-     * @type {boolean}
-     */
-    this.managed = data.managed;
-
-    /**
-     * Application ID of the application that made this Group DM, if applicable
-     * @type {?Snowflake}
-     */
-    this.applicationID = data.application_id;
-
-    if (data.nicks) {
-      /**
-       * Nicknames for group members
-       * @type {?Collection<Snowflake, string>}
-       */
-      this.nicks = new Collection(data.nicks.map(n => [n.id, n.nick]));
-    }
-
-    if (!this.recipients) {
-      /**
-       * A collection of the recipients of this DM, mapped by their ID
-       * @type {Collection<Snowflake, User>}
-       */
-      this.recipients = new Collection();
-    }
-
-    if (data.recipients) {
-      for (const recipient of data.recipients) {
-        const user = this.client.users.add(recipient);
-        this.recipients.set(user.id, user);
-      }
-    }
-
-    /**
-     * The ID of the last message in the channel, if one was sent
-     * @type {?Snowflake}
-     */
-    this.lastMessageID = data.last_message_id;
-
-    /**
-     * The timestamp when the last pinned message was pinned, if there was one
-     * @type {?number}
-     */
-    this.lastPinTimestamp = data.last_pin_timestamp ? new Date(data.last_pin_timestamp).getTime() : null;
-  }
-
-  /**
-   * The owner of this Group DM
-   * @type {?User}
-   * @readonly
-   */
-  get owner() {
-    return this.client.users.get(this.ownerID) || null;
-  }
-
-  /**
-   * Gets the URL to this Group DM's icon.
-   * @param {ImageURLOptions} [options={}] Options for the Image URL
-   * @returns {?string}
-   */
-  iconURL({ format, size } = {}) {
-    if (!this.icon) return null;
-    return this.client.rest.cdn.GDMIcon(this.id, this.icon, format, size);
-  }
-
-  /**
-   * Whether this channel equals another channel. It compares all properties, so for most operations
-   * it is advisable to just compare `channel.id === channel2.id` as it is much faster and is often
-   * what most users need.
-   * @param {GroupDMChannel} channel Channel to compare with
-   * @returns {boolean}
-   */
-  equals(channel) {
-    const equal = channel &&
-      this.id === channel.id &&
-      this.name === channel.name &&
-      this.icon === channel.icon &&
-      this.ownerID === channel.ownerID;
-
-    if (equal) {
-      return this.recipients.equals(channel.recipients);
-    }
-
-    return equal;
-  }
-
-  /**
-   * Edits this Group DM.
-   * @param {Object} data New data for this Group DM
-   * @param {string} [reason] Reason for editing this Group DM
-   * @returns {Promise<GroupDMChannel>}
-   */
-  edit(data, reason) {
-    return this.client.api.channels[this.id].patch({
-      data: {
-        icon: data.icon,
-        name: data.name === null ? null : data.name || this.name,
-      },
-      reason,
-    }).then(() => this);
-  }
-
-  /**
-   * Sets a new icon for this Group DM.
-   * @param {Base64Resolvable|BufferResolvable} icon The new icon of this Group DM
-   * @returns {Promise<GroupDMChannel>}
-   */
-  async setIcon(icon) {
-    return this.edit({ icon: await DataResolver.resolveImage(icon) });
-  }
-
-  /**
-   * Sets a new name for this Group DM.
-   * @param {string} name New name for this Group DM
-   * @returns {Promise<GroupDMChannel>}
-   */
-  setName(name) {
-    return this.edit({ name });
-  }
-
-  /**
-   * Adds a user to this Group DM.
-   * @param {Object} options Options for this method
-   * @param {UserResolvable} options.user User to add to this Group DM
-   * @param {string} [options.accessToken] Access token to use to add the user to this Group DM
-   * @param {string} [options.nick] Permanent nickname to give the user
-   * @returns {Promise<GroupDMChannel>}
-   */
-  addUser({ user, accessToken, nick }) {
-    const id = this.client.users.resolveID(user);
-    return this.client.api.channels[this.id].recipients[id].put({ nick, access_token: accessToken })
-      .then(() => this);
-  }
-
-  /**
-   * Removes a user from this Group DM.
-   * @param {UserResolvable} user User to remove
-   * @returns {Promise<GroupDMChannel>}
-   */
-  removeUser(user) {
-    const id = this.client.users.resolveID(user);
-    return this.client.api.channels[this.id].recipients[id].delete()
-      .then(() => this);
-  }
-
-  /**
-   * When concatenated with a string, this automatically returns the channel's name instead of the
-   * GroupDMChannel object.
-   * @returns {string}
-   * @example
-   * // Logs: Hello from My Group DM!
-   * console.log(`Hello from ${channel}!`);
-   */
-  toString() {
-    return this.name;
-  }
-
-  // These are here only for documentation purposes - they are implemented by TextBasedChannel
-  /* eslint-disable no-empty-function */
-  get lastMessage() {}
-  get lastPinAt() {}
-  send() {}
-  startTyping() {}
-  stopTyping() {}
-  get typing() {}
-  get typingCount() {}
-  createMessageCollector() {}
-  awaitMessages() {}
-  // Doesn't work on Group DMs; bulkDelete() {}
-  acknowledge() {}
-  _cacheMessage() {}
-}
-
-TextBasedChannel.applyToClass(GroupDMChannel, true, ['bulkDelete']);
-
-module.exports = GroupDMChannel;

src/structures/Guild.js

@@ -5,7 +5,7 @@ const Integration = require('./Integration');
 const GuildAuditLogs = require('./GuildAuditLogs');
 const Webhook = require('./Webhook');
 const VoiceRegion = require('./VoiceRegion');
-const { ChannelTypes, DefaultMessageNotifications, browser } = require('../util/Constants');
+const { ChannelTypes, DefaultMessageNotifications, PartialTypes, browser } = require('../util/Constants');
 const Collection = require('../util/Collection');
 const Util = require('../util/Util');
 const DataResolver = require('../util/DataResolver');
@@ -341,7 +341,9 @@ class Guild extends Base {
    * @readonly
    */
   get owner() {
-    return this.members.get(this.ownerID) || null;
+    return this.members.get(this.ownerID) || (this.client.options.partials.includes(PartialTypes.GUILD_MEMBER) ?
+      this.members.add({ user: { id: this.ownerID } }, true) :
+      null);
   }
 
   /**

src/structures/GuildAuditLogs.js

@@ -4,6 +4,7 @@ const Collection = require('../util/Collection');
 const Snowflake = require('../util/Snowflake');
 const Webhook = require('./Webhook');
 const Util = require('../util/Util');
+const PartialTypes = require('../util/Constants');
 
 /**
  * The target type of an entry, e.g. `GUILD`. Here are the available types:
@@ -234,7 +235,7 @@ class GuildAuditLogs {
  * Audit logs entry.
  */
 class GuildAuditLogsEntry {
-  constructor(logs, guild, data) {
+  constructor(logs, guild, data) { // eslint-disable-line complexity
     const targetType = GuildAuditLogs.targetType(data.action_type);
     /**
      * The target type of this entry
@@ -264,7 +265,9 @@ class GuildAuditLogsEntry {
      * The user that executed this entry
      * @type {User}
      */
-    this.executor = guild.client.users.get(data.user_id);
+    this.executor = guild.client.options.partials.includes(PartialTypes.USER) ?
+      guild.client.users.add({ id: data.user_id }) :
+      guild.client.users.get(data.user_id);
 
     /**
      * An entry in the audit log representing a specific change.
@@ -329,8 +332,12 @@ class GuildAuditLogsEntry {
         return o;
       }, {});
       this.target.id = data.target_id;
-    } else if ([Targets.USER, Targets.GUILD].includes(targetType)) {
+    } else if (targetType === Targets.USER) {
-      this.target = guild.client[`${targetType.toLowerCase()}s`].get(data.target_id);
+      this.target = guild.client.options.partials.includes(PartialTypes.USER) ?
+        guild.client.users.add({ id: data.target_id }) :
+        guild.client.users.get(data.target_id);
+    } else if (targetType === Targets.GUILD) {
+      this.target = guild.client.guilds.get(data.target_id);
     } else if (targetType === Targets.WEBHOOK) {
       this.target = logs.webhooks.get(data.target_id) ||
         new Webhook(guild.client,

src/structures/GuildMember.js

@@ -28,7 +28,7 @@ class GuildMember extends Base {
      * The user that this guild member instance represents
      * @type {User}
      */
-    this.user = {};
+    if (data.user) this.user = client.users.add(data.user, true);
 
     /**
      * The timestamp the member joined the guild at
@@ -79,6 +79,14 @@ class GuildMember extends Base {
     return clone;
   }
 
+  /**
+   * Whether this GuildMember is a partial
+   * @type {boolean}
+   */
+  get partial() {
+    return !this.joinedTimestamp;
+  }
+
   /**
    * A collection of roles that are applied to this member, mapped by the role ID
    * @type {GuildMemberRoleStore<Snowflake, Role>}
@@ -355,6 +363,14 @@ class GuildMember extends Base {
     return this.guild.members.ban(this, options);
   }
 
+  /**
+   * Fetches this GuildMember.
+   * @returns {Promise<GuildMember>}
+   */
+  fetch() {
+    return this.guild.members.fetch(this.id, true);
+  }
+
   /**
    * When concatenated with a string, this automatically returns the user's mention instead of the GuildMember object.
    * @returns {string}

src/structures/Message.js

@@ -24,7 +24,7 @@ class Message extends Base {
 
     /**
      * The channel that the message was sent in
-     * @type {TextChannel|DMChannel|GroupDMChannel}
+     * @type {TextChannel|DMChannel}
      */
     this.channel = channel;
 
@@ -60,7 +60,7 @@ class Message extends Base {
      * The author of the message
      * @type {User}
      */
-    this.author = this.client.users.add(data.author, !data.webhook_id);
+    this.author = data.author ? this.client.users.add(data.author, !data.webhook_id) : null;
 
     /**
      * Whether or not this message is pinned
@@ -90,17 +90,19 @@ class Message extends Base {
      * A list of embeds in the message - e.g. YouTube Player
      * @type {MessageEmbed[]}
      */
-    this.embeds = data.embeds.map(e => new Embed(e));
+    this.embeds = (data.embeds || []).map(e => new Embed(e));
 
     /**
      * A collection of attachments in the message - e.g. Pictures - mapped by their ID
      * @type {Collection<Snowflake, MessageAttachment>}
      */
     this.attachments = new Collection();
-    for (const attachment of data.attachments) {
+    if (data.attachments) {
-      this.attachments.set(attachment.id, new MessageAttachment(
+      for (const attachment of data.attachments) {
-        attachment.url, attachment.filename, attachment
+        this.attachments.set(attachment.id, new MessageAttachment(
-      ));
+          attachment.url, attachment.filename, attachment
+        ));
+      }
     }
 
     /**
@@ -167,6 +169,14 @@ class Message extends Base {
     }
   }
 
+  /**
+   * Whether or not this message is a partial
+   * @type {boolean}
+   */
+  get partial() {
+    return typeof this.content !== 'string' || !this.author;
+  }
+
   /**
    * Updates the message.
    * @param {Object} data Raw Discord message update data
@@ -472,6 +482,14 @@ class Message extends Base {
     );
   }
 
+  /**
+   * Fetch this message.
+   * @returns {Promise<Message>}
+   */
+  fetch() {
+    return this.channel.messages.fetch(this.id, true);
+  }
+
   /**
    * Fetches the webhook used to create this message.
    * @returns {Promise<?Webhook>}

src/structures/MessageCollector.js

@@ -15,7 +15,7 @@ const { Events } = require('../util/Constants');
  */
 class MessageCollector extends Collector {
   /**
-   * @param {TextChannel|DMChannel|GroupDMChannel} channel The channel
+   * @param {TextChannel|DMChannel} channel The channel
    * @param {CollectorFilter} filter The filter to be applied to this collector
    * @param {MessageCollectorOptions} options The options to be applied to this collector
    * @emits MessageCollector#message

src/structures/User.js

@@ -53,6 +53,8 @@ class User extends Base {
      */
     if (typeof data.avatar !== 'undefined') this.avatar = data.avatar;
 
+    if (typeof data.bot !== 'undefined') this.bot = Boolean(data.bot);
+
     /**
      * The locale of the user's client (ISO 639-1)
      * @type {?string}
@@ -73,6 +75,14 @@ class User extends Base {
     this.lastMessageChannelID = null;
   }
 
+  /**
+   * Whether this User is a partial
+   * @type {boolean}
+   */
+  get partial() {
+    return typeof this.username !== 'string';
+  }
+
   /**
    * The timestamp the user was created at
    * @type {number}
@@ -228,6 +238,14 @@ class User extends Base {
     return equal;
   }
 
+  /**
+   * Fetches this user.
+   * @returns {Promise<User>}
+   */
+  fetch() {
+    return this.client.users.fetch(this.id, true);
+  }
+
   /**
    * When concatenated with a string, this automatically returns the user's mention instead of the User object.
    * @returns {string}

src/util/Constants.js

@@ -21,6 +21,9 @@ const browser = exports.browser = typeof window !== 'undefined';
  * @property {boolean} [fetchAllMembers=false] Whether to cache all guild members and users upon startup, as well as
  * upon joining a guild (should be avoided whenever possible)
  * @property {boolean} [disableEveryone=false] Default value for {@link MessageOptions#disableEveryone}
+ * @property {PartialType[]} [partials] Structures allowed to be partial. This means events can be emitted even when
+ * they're missing all the data for a particular structure. See the "Partials" topic listed in the sidebar for some
+ * important usage information, as partials require you to put checks in place when handling data.
  * @property {number} [restWsBridgeTimeout=5000] Maximum time permitted between REST responses and their
  * corresponding websocket events
  * @property {number} [restTimeOffset=500] Extra time in millseconds to wait before continuing to make REST
@@ -44,6 +47,7 @@ exports.DefaultOptions = {
   messageSweepInterval: 0,
   fetchAllMembers: false,
   disableEveryone: false,
+  partials: [],
   restWsBridgeTimeout: 5000,
   disabledEvents: [],
   retryLimit: 1,
@@ -261,6 +265,23 @@ exports.Events = {
   RAW: 'raw',
 };
 
+/**
+ * The type of Structure allowed to be a partial:
+ * * USER
+ * * CHANNEL (only affects DMChannels)
+ * * GUILD_MEMBER
+ * * MESSAGE
+ * <warn>Partials require you to put checks in place when handling data, read the Partials topic listed in the
+ * sidebar for more information.</warn>
+ * @typedef {string} PartialType
+ */
+exports.PartialTypes = keyMirror([
+  'USER',
+  'CHANNEL',
+  'GUILD_MEMBER',
+  'MESSAGE',
+]);
+
 /**
  * The type of a websocket message event, e.g. `MESSAGE_CREATE`. Here are the available events:
  * * READY

src/util/Structures.js

@@ -67,7 +67,6 @@ class Structures {
 const structures = {
   GuildEmoji: require('../structures/GuildEmoji'),
   DMChannel: require('../structures/DMChannel'),
-  GroupDMChannel: require('../structures/GroupDMChannel'),
   TextChannel: require('../structures/TextChannel'),
   VoiceChannel: require('../structures/VoiceChannel'),
   CategoryChannel: require('../structures/CategoryChannel'),

src/util/Util.js

@@ -395,7 +395,7 @@ class Util {
       .replace(/@(everyone|here)/g, '@\u200b$1')
       .replace(/<@!?[0-9]+>/g, input => {
         const id = input.replace(/<|!|>|@/g, '');
-        if (message.channel.type === 'dm' || message.channel.type === 'group') {
+        if (message.channel.type === 'dm') {
           const user = message.client.users.get(id);
           return user ? `@${user.username}` : input;
         }
@@ -413,7 +413,7 @@ class Util {
         return channel ? `#${channel.name}` : input;
       })
       .replace(/<@&[0-9]+>/g, input => {
-        if (message.channel.type === 'dm' || message.channel.type === 'group') return input;
+        if (message.channel.type === 'dm') return input;
         const role = message.guild.roles.get(input.replace(/<|@|>|&/g, ''));
         return role ? `@${role.name}` : input;
       });

test/voice.js

@@ -6,7 +6,7 @@ const ytdl = require('ytdl-core');
 const prism = require('prism-media');
 const fs = require('fs');
 
-const client = new Discord.Client({ fetchAllMembers: false, apiRequestMethod: 'sequential' });
+const client = new Discord.Client({ fetchAllMembers: false, partials: true, apiRequestMethod: 'sequential' });
 
 const auth = require('./auth.js');
 
@@ -34,6 +34,15 @@ client.on('presenceUpdate', (a, b) => {
   console.log(a ? a.status : null, b.status, b.user.username);
 });
 
+client.on('messageDelete', async (m) => {
+  if (m.channel.id != '80426989059575808') return;
+  console.log(m.channel.recipient);
+  console.log(m.channel.partial);
+  await m.channel.fetch();
+  console.log('\n\n\n\n');
+  console.log(m.channel);
+});
+
 client.on('message', m => {
   if (!m.guild) return;
   if (m.author.id !== '66564597481480192') return;

typings/index.d.ts

@@ -129,8 +129,9 @@ declare module 'discord.js' {
 		public readonly createdTimestamp: number;
 		public deleted: boolean;
 		public id: Snowflake;
-		public type: 'dm' | 'group' | 'text' | 'voice' | 'category' | 'unknown';
+		public type: 'dm' | 'text' | 'voice' | 'category' | 'unknown';
 		public delete(reason?: string): Promise<Channel>;
+		public fetch(): Promise<Channel>;
 		public toString(): string;
 	}
 
@@ -264,7 +265,6 @@ declare module 'discord.js' {
 	export class ClientUser extends User {
 		public mfaEnabled: boolean;
 		public verified: boolean;
-		public createGroupDM(recipients: GroupDMRecipientOptions[]): Promise<GroupDMChannel>;
 		public setActivity(options?: ActivityOptions): Promise<Presence>;
 		public setActivity(name: string, options?: ActivityOptions): Promise<Presence>;
 		public setAFK(afk: boolean): Promise<Presence>;
@@ -360,6 +360,7 @@ declare module 'discord.js' {
 		constructor(client: Client, data?: object);
 		public messages: MessageStore;
 		public recipient: User;
+		public readonly partial: boolean;
 	}
 
 	export class Emoji extends Base {
@@ -376,26 +377,6 @@ declare module 'discord.js' {
 		public toString(): string;
 	}
 
-	export class GroupDMChannel extends TextBasedChannel(Channel) {
-		constructor(client: Client, data?: object);
-		public applicationID: Snowflake;
-		public icon: string;
-		public managed: boolean;
-		public messages: MessageStore;
-		public name: string;
-		public nicks: Collection<Snowflake, string>;
-		public readonly owner: User;
-		public ownerID: Snowflake;
-		public recipients: Collection<Snowflake, User>;
-		public addUser(options: { user: UserResolvable, accessToken?: string, nick?: string }): Promise<GroupDMChannel>;
-		public edit (data: { icon?: string, name?: string }): Promise<GroupDMChannel>;
-		public equals(channel: GroupDMChannel): boolean;
-		public iconURL(options?: AvatarOptions): string;
-		public removeUser(user: UserResolvable): Promise<GroupDMChannel>;
-		public setIcon(icon: Base64Resolvable | BufferResolvable): Promise<GroupDMChannel>;
-		public setName(name: string): Promise<GroupDMChannel>;
-	}
-
 	export class Guild extends Base {
 		constructor(client: Client, data: object);
 		private _sortedRoles(): Collection<Snowflake, Role>;
@@ -570,12 +551,14 @@ declare module 'discord.js' {
 		public readonly kickable: boolean;
 		public readonly manageable: boolean;
 		public nickname: string;
+		public readonly partial: boolean;
 		public readonly permissions: Readonly<Permissions>;
 		public readonly presence: Presence;
 		public roles: GuildMemberRoleStore;
 		public user: User;
 		public readonly voice: VoiceState;
 		public ban(options?: BanOptions): Promise<GuildMember>;
+		public fetch(): Promise<GuildMember>;
 		public createDM(): Promise<DMChannel>;
 		public deleteDM(): Promise<DMChannel>;
 		public edit(data: GuildMemberEditData, reason?: string): Promise<GuildMember>;
@@ -619,7 +602,7 @@ declare module 'discord.js' {
 
 	export class Invite extends Base {
 		constructor(client: Client, data: object);
-		public channel: GuildChannel | GroupDMChannel;
+		public channel: GuildChannel;
 		public code: string;
 		public readonly createdAt: Date;
 		public createdTimestamp: number;
@@ -640,7 +623,7 @@ declare module 'discord.js' {
 	}
 
 	export class Message extends Base {
-		constructor(client: Client, data: object, channel: TextChannel | DMChannel | GroupDMChannel);
+		constructor(client: Client, data: object, channel: TextChannel | DMChannel);
 		private _edits: Message[];
 		private patch(data: object): void;
 
@@ -648,7 +631,7 @@ declare module 'discord.js' {
 		public application: ClientApplication;
 		public attachments: Collection<Snowflake, MessageAttachment>;
 		public author: User;
-		public channel: TextChannel | DMChannel | GroupDMChannel;
+		public channel: TextChannel | DMChannel;
 		public readonly cleanContent: string;
 		public content: string;
 		public readonly createdAt: Date;
@@ -665,6 +648,7 @@ declare module 'discord.js' {
 		public readonly member: GuildMember;
 		public mentions: MessageMentions;
 		public nonce: string;
+		public readonly partial: boolean;
 		public readonly pinnable: boolean;
 		public pinned: boolean;
 		public reactions: ReactionStore;
@@ -680,6 +664,7 @@ declare module 'discord.js' {
 		public edit(options: MessageEditOptions | MessageEmbed | APIMessage): Promise<Message>;
 		public equals(message: Message, rawData: object): boolean;
 		public fetchWebhook(): Promise<Webhook>;
+		public fetch(): Promise<Message>;
 		public pin(): Promise<Message>;
 		public react(emoji: EmojiIdentifierResolvable): Promise<MessageReaction>;
 		public reply(content?: StringResolvable, options?: MessageOptions | MessageAdditions): Promise<Message | Message[]>;
@@ -706,7 +691,7 @@ declare module 'discord.js' {
 	}
 
 	export class MessageCollector extends Collector<Snowflake, Message> {
-		constructor(channel: TextChannel | DMChannel | GroupDMChannel, filter: CollectorFilter, options?: MessageCollectorOptions);
+		constructor(channel: TextChannel | DMChannel, filter: CollectorFilter, options?: MessageCollectorOptions);
 		public channel: Channel;
 		public options: MessageCollectorOptions;
 		public received: number;
@@ -1078,6 +1063,7 @@ declare module 'discord.js' {
 		public readonly dmChannel: DMChannel;
 		public id: Snowflake;
 		public locale: string;
+		public readonly partial: boolean;
 		public readonly presence: Presence;
 		public readonly tag: string;
 		public username: string;
@@ -1086,6 +1072,7 @@ declare module 'discord.js' {
 		public deleteDM(): Promise<DMChannel>;
 		public displayAvatarURL(options?: AvatarOptions): string;
 		public equals(user: User): boolean;
+		public fetch(): Promise<User>;
 		public toString(): string;
 		public typingDurationIn(channel: ChannelResolvable): number;
 		public typingIn(channel: ChannelResolvable): boolean;
@@ -1385,7 +1372,7 @@ declare module 'discord.js' {
 	}
 
 	export class MessageStore extends DataStore<Snowflake, Message, typeof Message, MessageResolvable> {
-		constructor(channel: TextChannel | DMChannel | GroupDMChannel, iterable?: Iterable<any>);
+		constructor(channel: TextChannel | DMChannel, iterable?: Iterable<any>);
 		public fetch(message: Snowflake): Promise<Message>;
 		public fetch(options?: ChannelLogsQueryOptions): Promise<Collection<Snowflake, Message>>;
 		public fetchPinned(): Promise<Collection<Snowflake, Message>>;
@@ -1607,6 +1594,7 @@ declare module 'discord.js' {
 		messageSweepInterval?: number;
 		fetchAllMembers?: boolean;
 		disableEveryone?: boolean;
+		partials?: PartialTypes[];
 		restWsBridgeTimeout?: number;
 		restTimeOffset?: number;
 		restSweepInterval?: number;
@@ -1676,7 +1664,6 @@ declare module 'discord.js' {
 	type Extendable = {
 		GuildEmoji: typeof GuildEmoji;
 		DMChannel: typeof DMChannel;
-		GroupDMChannel: typeof GroupDMChannel;
 		TextChannel: typeof TextChannel;
 		VoiceChannel: typeof VoiceChannel;
 		CategoryChannel: typeof CategoryChannel;
@@ -1711,13 +1698,6 @@ declare module 'discord.js' {
 		type: number;
 	};
 
-	type GroupDMRecipientOptions = {
-		user?: UserResolvable | Snowflake;
-		accessToken?: string;
-		nick?: string;
-		id?: Snowflake;
-	};
-
 	type GuildAuditLogsAction = keyof GuildAuditLogsActions;
 
 	type GuildAuditLogsActions = {
@@ -1934,7 +1914,7 @@ declare module 'discord.js' {
 
 	type MessageResolvable = Message | Snowflake;
 
-	type MessageTarget = TextChannel | DMChannel | GroupDMChannel | User | GuildMember | Webhook | WebhookClient;
+	type MessageTarget = TextChannel | DMChannel | User | GuildMember | Webhook | WebhookClient;
 
 	type MessageType = 'DEFAULT'
 		| 'RECIPIENT_ADD'
@@ -2023,6 +2003,11 @@ declare module 'discord.js' {
 		desktop?: ClientPresenceStatus
 	};
 
+	type PartialTypes = 'USER'
+		| 'CHANNEL'
+		| 'GUILD_MEMBER'
+		| 'MESSAGE';
+
 	type PresenceStatus = ClientPresenceStatus | 'offline';
 
 	type PresenceStatusData = ClientPresenceStatus | 'invisible';