backport(Guild): add fetchVanityCode (#2871)

src/client/rest/RESTMethods.js

@@ -684,6 +684,11 @@ class RESTMethods {
     });
   }
 
+  getGuildVanityCode(guild) {
+    return this.rest.makeRequest('get', Endpoints.Guild(guild).vanityURL, true)
+      .then(res => res.code);
+  }
+
   pruneGuildMembers(guild, days, dry, reason) {
     return this.rest.makeRequest(dry ?
       'get' :

src/structures/Guild.js

@@ -504,6 +504,26 @@ class Guild {
     return this.client.rest.methods.getGuildInvites(this);
   }
 
+  /**
+   * Fetches the vanity url invite code to this guild.
+   * Resolves with a string matching the vanity url invite code, not the full url.
+   * @returns {Promise<string>}
+   * @example
+   * // Fetch invites
+   * guild.fetchVanityCode()
+   *   .then(code => {
+   *     console.log(`Vanity URL: https://discord.gg/${code}`);
+   *   })
+   *   .catch(console.error);
+   */
+  fetchVanityCode() {
+    if (!this.features.includes('VANITY_URL')) {
+      return Promise.reject(new Error('This guild does not have the VANITY_URL feature enabled.'));
+    }
+    return this.client.rest.methods.getGuildVanityCode(this);
+  }
+
+
   /**
    * Fetch all webhooks for the guild.
    * @returns {Promise<Collection<Snowflake, Webhook>>}

src/util/Constants.js

@@ -144,6 +144,7 @@ const Endpoints = exports.Endpoints = {
       roles: `${base}/roles`,
       emojis: `${base}/emojis`,
       search: `${base}/messages/search`,
+      vanityURL: `${base}/vanity-url`,
       voiceRegions: `${base}/regions`,
       webhooks: `${base}/webhooks`,
       ack: `${base}/ack`,

typings/index.d.ts

@@ -537,6 +537,7 @@ declare module 'discord.js' {
 		public fetchInvites(): Promise<Collection<Snowflake, Invite>>;
 		public fetchMember(user: UserResolvable, cache?: boolean): Promise<GuildMember>;
 		public fetchMembers(query?: string, limit?: number): Promise<Guild>;
+		public fetchVanityCode(): Promise<string>;
 		public fetchVoiceRegions(): Promise<Collection<string, VoiceRegion>>;
 		public fetchWebhooks(): Promise<Collection<Snowflake, Webhook>>;
 		public leave(): Promise<Guild>;