Discord.js音乐机器人AudioPlayer.play报Cannot read 'once'错误求助

错误修复方案 #

核心问题定位

• @discordjs/voice的AudioPlayer.play()方法仅接受AudioResource类型的参数，你直接传入ytdl返回的裸流不符合接口要求，这是触发Cannot read properties of undefined (reading 'once')报错的直接原因
• play.js中未定义connection变量就直接调用connection.subscribe()，同时播放逻辑和加入语音频道的逻辑割裂，没有在执行play命令时自动初始化语音连接
• index.js中命令注册逻辑写错，你的普通命令导出的是name字段，用command.data.name取值会返回undefined，会导致命令注册失败

修正后的play.js代码

const ytdl = require('ytdl-core');
const ytSearch = require('yt-search');
const {
  createAudioPlayer,
  createAudioResource,
  joinVoiceChannel,
  getVoiceConnection
} = require('@discordjs/voice');

const player = createAudioPlayer();

module.exports = {
    name: 'play',
    description: 'Plays video',
    async execute(message, args) {
        const voiceChannel = message.member.voice.channel;
        if (!voiceChannel) return message.channel.send('I cannot enter the tavern!');
        const permissions = voiceChannel.permissionsFor(message.client.user);
        if (!permissions.has('CONNECT')) return message.channel.send('I cannot reach you!');
        if (!permissions.has('SPEAK')) return message.channel.send('I cannot hear you!');
        if (!args.length) return message.channel.send('You need to tell me the song!');
        
        const videoFinder = async (query) => {
          const videoResult = await ytSearch(query);
          return videoResult.videos.length >= 1 ? videoResult.videos[0] : null;
        }
        const video = await videoFinder(args.join(' '));
        if(video){
            // 先获取已有的语音连接，没有就新建连接
            let connection = getVoiceConnection(message.guild.id);
            if (!connection) {
                connection = joinVoiceChannel({
                    channelId: voiceChannel.id,
                    guildId: message.guild.id,
                    adapterCreator: message.guild.voiceAdapterCreator
                });
            }
            // 将ytdl流包装为AudioResource
            const stream = ytdl(video.url, {filter: 'audioonly', highWaterMark: 1<<25});
            const resource = createAudioResource(stream, { inlineVolume: true });
            resource.volume.setVolume(0.5);
            // 播放资源、订阅播放器
            player.play(resource);
            connection.subscribe(player);
            await message.reply(`:thumbsup: Now Playing *${video.title}*`);
        } else {
            message.channel.send(`No video results found`);
        }
    }
}

修正index.js的两处问题

1. 替换命令注册逻辑：
   把原来的循环

for (const file of commandFiles) {
    const command = require(`./commands/${file}`);
    client.commands.set(command.data.name, command);
}

替换为

for (const file of commandFiles) {
    const command = require(`./commands/${file}`);
    client.commands.set(command.name, command);
}

2. 替换废弃事件：discord.js v14已经弃用message事件，把client.on('message', message => {改成client.on('messageCreate', message => {即可适配版本规范。

内容的提问来源于stack exchange，提问作者Aegis