问猫鼬文档_id是空的，所以当我尝试保存时，我得到MongooseError:文档必须在保存之前具有和id。

EN

Starting...
Online! Logged in as Amazon Price Tracker#6927
Connected to Database
null
MongooseError: document must have an _id before saving
    at C:\Users\logic\Documents\Disc Bot\node_modules\mongoose\lib\model.js:291:18
    at processTicksAndRejections (node:internal/process/task_queues:78:11)
Disconnected from Database

//add function using mongoose for mongodb
const { SlashCommandBuilder } = require("@discordjs/builders");

const mongoose = require("mongoose");
const { MongoDBurl } = require("../config.json");
const Link = require("../Schemas/Link.js");

module.exports = {
    //Build the slash command
    data: new SlashCommandBuilder()
    .setName("add")
    .setDescription("add a url to watch list")
    .addStringOption(option =>
        option.setName("url")
            .setDescription("url to add to watch list")
            .setRequired(true),
        ),

    //Function that runs when the command is used
    async execute (interaction) {
        const URL = interaction.options.getString("url");
        const user = interaction.user.username;

        await interaction.reply(`On it! Adding ${URL} to your watch list`)

        //Connect to the database, throws an error if it can't connect
        await mongoose.connect(MongoDBurl)
            .then( () => console.log("Connected to Database"))
            .catch(err => console.log(err));

        //Check if the link is already in the database
        var exists = await Link.exists({ link: URL}).exec()
                    .catch(err => console.log(err))

        if (exists) {
            console.log("This Document Already Exists")
            interaction.editReply(`Oops! That link is already in my database.`)
        } else {
            //If the link dosen't exist, create a document and save it to the database
            var newLink = new Link({ user: user }, { link: URL }, { price: "N/A" })
            // Debuging variable
            var a = newLink.id;
            console.log(a)

            await newLink.save()
                .then( () => {
                    console.log("Document Saved")
                    interaction.editReply(`All done! I have saved ${URL} to your watch list.`)
                })
                .catch(err => {
                    console.log(err)
                    interaction.editReply("Oops! Something went wrong, I wasen't able to save this link.")
                })
        }

        //Close the connection when we finish
        await mongoose.connection.close()
            .then( () => console.log("Disconnected from Database"))
    }
};

const mongoose = require("mongoose");
const Schema = mongoose.Schema;

const LinkSchema = new Schema({
    user: {
        type: String,
        requiered: true
    },
    link: {
        type: String,
        requiered: true
    },
    price: {
        type: String,
        requiered: true
    },
})

module.exports = mongoose.model("Link", LinkSchema);