welcome.js

const { Command } = require('discord.js-commando');
const mongo = require('../../mongo');
const WelcomeSchema = require('../../models/welcomeSchema');

const cache = {}

module.exports = class WelcomeSetCommand extends Command {
    constructor(client) {
        super(client, {
            name: 'setwelcome',
            group: 'server-config',
            memberName: 'setwelcome',
            description: 'A command that sets a welcome message.',
            userPermissions: ['ADMINISTRATOR'],
            args: [
                {
                    key: 'message',
                    prompt: 'What do want to say when a new user joins?',
                    type: 'string'
                }
            ]
        })
    }

    async run (msg, { message }) {
        const { channel, guild } = msg;

        cache[guild.id] = [channel.id, message]

        await mongo().then(async (mongoose) => {
            try{
                await WelcomeSchema.findOneAndUpdate({
                    _id: guild.id
                }, {
                    _id: guild.id,
                    channelId: channel.id,
                    text: message
                }, {
                    upsert: true
                })
            } finally{
                mongoose.connection.close()
            }
        })
    }
}