这是我的代码（index.js），（auth.js）

const express = require("express");
const dotenv = require("dotenv");
const mongoose = require("mongoose");
const authRoute = require("./routes/auth");
const app = express();

dotenv.config();
app.use(express.json());

mongoose.connect(process.env.MONGO_URL, {
    useNewUrlParser: true,
    useUnifiedTopology: true,
    useCreateIndex: true,
  }).then(console.log("Connected to MongoDB"))
  .catch((err) => console.log("err"));
app.use("/api/auth",authRoute );

app.use("/api/auth",authRoute);

app.listen("3000", () => {
  console.log("Backend is running.");
});

const router = require("express").Router();
const User = require("../models/User");

//REGISTER
router.post("/register", async (req, res) => {
  try {
    const newUser = new User({
      username: req.body.username,
      email: req.body.email,
      password: req.body.password,
    });

    const user = await newUser.save();
    res.status(200).json(user);
  } catch (err) {
    res.status(500).json(err);
  }
});

//LOGIN

module.exports = router;
and image of the postman result

当我发送请求时， Postman 的帖子空花括号。我想在 Postman 的身体下面得到帖子数据
screenshot of the postman
这是终端记录的内容result on the terminal