• to add data, use POST method
• POST method: request "body"(include additional infos) and send to server

routers/goods.js

router.post('/goods', async (req, res) => {
    const {goodsId, name, thumbnailUrl, category, price} = req.body;  // assign seperately

    const isExist = await Goods.find({ goodsId });

    if (isExist.length == 0) {  // no duplicated
        await Goods.create({ goodsId, name, thumbnailUrl, category, price });
    }

    res.send({result: "success"});
});

→ to get POST method's return value, we need "insomnia"