如果某个成员上线，Discord bot 会发送消息

Question

过去几天我一直在进行研究，但实际上找不到任何东西。在 python 中也是如此。

const Discord = require("discord.js")
const client = new Discord.Client({ intents: ["GUILDS", "GUILD_MESSAGES"] })

const member = client.guilds.cache.get("person_id") // person I want to check

client.on("ready", () => {
   console.log(`Logged in as ${client.user.tag}!`)
})

client.on("message", msg => {
   if (msg.content === "ping") {
      msg.reply("pong");
   }
}) // everything worked to this moment

client.on("presenceUpdate", () => {
   if (member.presence.status === 'online') {
      client.channels.cache.get("channel_id").send("HELLO"); // message i want bot send to the channel if member goes online
   }
});

client.login('***')

如果我添加 GUILD_PRESENCES 意图，我会收到以下错误：

if (member.presence.status === 'online') { 
           ^ TypeError: Cannot read properties of undefined (reading 'presence')

Answer 1

首先，如果您想使用presenceUpdate 事件，您需要enable the GUILD_PRESENCES intent。

其次，client.guilds.cache.get("person_id") 不返回成员。 guilds.cache 是公会的集合，而不是成员。

最后，presenceUpdate 会在成员的状态（例如状态、活动）发生变化时触发。这意味着他们的presence 可以相同（例如在线），但事件仍然会触发，因此检查if (member.presence.status === 'online') 将不起作用。您可以做的是比较新旧presences。您可以在下面找到代码，我添加了一些 cmets 使其更清晰。

const Discord = require('discord.js');
const client = new Discord.Client({
  intents: ['GUILDS', 'GUILD_MESSAGES', 'GUILD_PRESENCES'],
});

client.on('ready', () => {
  console.log(`Logged in as ${client.user.tag}!`);
});

client.on('presenceUpdate', (oldPresence, newPresence) => {
  // if someone else has updated their status, just return
  if (newPresence.userId !== 'person_id') return;
  // if it's not the status that has changed, just return
  if (oldPresence.status === newPresence.status) return;
  // of if the new status is not online, again, just return
  if (newPresence.status !== 'online') return;

  try {
    client.channels.cache.get('channel_id').send('HELLO');
  } catch (error) {
    console.log(error);
  }
});

client.login('***');