MySQL 在 discord.js

Question

我正在设置一个机器人来使用 MySQL 数据库。 它之前有效，现在在我添加 MySQL 代码后它不起作用：

(node:12312) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'query' of undefined
    at C:\Users\Admin\Desktop\MuffinMod Data\MuffinMod - Recode\Bot\events\ready.js:4:20
    at Map.forEach (<anonymous>)
    at module.exports (C:\Users\Admin\Desktop\MuffinMod Data\MuffinMod - Recode\Bot\events\ready.js:3:25)
    at Client.emit (events.js:315:20)
    at WebSocketManager.triggerClientReady (C:\Users\Admin\Desktop\MuffinMod Data\MuffinMod - Recode\node_modules\discord.js\src\client\websocket\WebSocketManager.js:431:17)
    at WebSocketManager.checkShardsReady (C:\Users\Admin\Desktop\MuffinMod Data\MuffinMod - Recode\node_modules\discord.js\src\client\websocket\WebSocketManager.js:415:10)
    at WebSocketShard.<anonymous> (C:\Users\Admin\Desktop\MuffinMod Data\MuffinMod - Recode\node_modules\discord.js\src\client\websocket\WebSocketManager.js:197:14)
    at WebSocketShard.emit (events.js:315:20)
    at WebSocketShard.checkReady (C:\Users\Admin\Desktop\MuffinMod Data\MuffinMod - Recode\node_modules\discord.js\src\client\websocket\WebSocketShard.js:475:12)
    at WebSocketShard.onPacket (C:\Users\Admin\Desktop\MuffinMod Data\MuffinMod - Recode\node_modules\discord.js\src\client\websocket\WebSocketShard.js:447:16)
(node:12312) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function 
without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)       
(node:12312) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

index.js：

require('dotenv').config();

//Database
let connection;
(async () => {
    connection = await require('./database/db.js');
})();
//Bot
const Discord = require("discord.js");
const client = new Discord.Client({ partials: ['MESSAGE', 'CHANNEL', 'REACTION'], restRequestTimeout: 50000 });
const guildSettings = new Map();
client.commands = new Discord.Collection();
client.events = new Discord.Collection();
const DisTube = require('distube');
client.distube = new DisTube(client, { searchSongs: false, emitNewSongOnly: true });
['command', 'event'].forEach(handler =>{
    require(`./Bot/handlers/${handler}`)(client, Discord, connection);
});
await client.login(process.env.TOKEN);

准备好了.js：

module.exports = async(Discord, client, connection) => {
    console.log(`Bot online. (${client.user.tag})`);
    client.guilds.cache.forEach(guild => {
        connection.query(
            `SELECT * FROM GuildConfigurable WHERE guildID = ${guild.id}`
        ).then(result => {
            guildSettings.set(guild.id, result[0][0]);
        }).catch(err => console.log(err));
    });
}

db.js：

const sql = require('mysql2/promise');
module.exports = sql.createConnection({
    host: process.env.DB_HOST,
    port: process.env.DB_PORT,
    user: process.env.DB_USERNAME,
    password: process.env.DB_PASSWORD,
    database: process.env.DB_NAME,
})
.then(()=>console.log(`Connected to MySQL Database.`))
.catch(err=>console.error(err));

我认为这是在 db.js 文件可以返回连接之前执行的 ready.js 文件的错误，但不知道如何修复它。 谢谢

Answer 1

由于您的async方法仅在 promise 解决后才设置connection变量，因此在您使用它来设置事件处理程序时它仍然是未定义的。

您可以将connection保持为每次需要时等待的 promise，或者将创建移动到与消费者相同的异步 function 中（如下所示）

require('dotenv').config();

//Bot
const Discord = require("discord.js");
const client = new Discord.Client({ partials: ['MESSAGE', 'CHANNEL', 'REACTION'], restRequestTimeout: 50000 });
const guildSettings = new Map();
client.commands = new Discord.Collection();
client.events = new Discord.Collection();
const DisTube = require('distube');
client.distube = new DisTube(client, { searchSongs: false, emitNewSongOnly: true });

(async () => {
    const connection = await require('./database/db.js');

    ['command', 'event'].forEach(handler =>{
      require(`./Bot/handlers/${handler}`)(client, Discord, connection);
});

    await client.login(process.env.TOKEN);

})();

在db.js ，您还需要从Promise链的最后一步返回connection ：

const sql = require('mysql2/promise');
module.exports = sql.createConnection({
    host: process.env.DB_HOST,
    port: process.env.DB_PORT,
    user: process.env.DB_USERNAME,
    password: process.env.DB_PASSWORD,
    database: process.env.DB_NAME,
})
.then((connection) => {
    console.log(`Connected to MySQL Database.`);
    return connection;
})
.catch(err=>console.error(err));