OverwriteModelError: Cannot overwrite `user` model once compiled - node.js

Question

I am facing this issue. I looked online for hours to find out what the problem is before posting here. I keep getting this error OverwriteModelError: Cannot overwrite ``user`` model once compiled. after sending a post request via postman and I can't find out what's going on. could you help me find out what's going on? thank you so much in advance!
server.js
const express = require("express");
const app = express();
const user = require("./routes/user");
const connectDB = require("./config/db");
connectDB();
app.use(express.json({extended: false}));
app.get("/", (req, res) => {
res.send("welcome to our api");
});
app.use("/user", user);
const PORT = 3000 || process.env.PORT;
app.listen(PORT, () => {
console.log(`PORT ${PORT} listening and refeshing...`);
});
db.js
const mongoose = require("mongoose");
const connectDB = () =>
mongoose
.connect(
"some database",
{
useNewUrlParser: true,
useUnifiedTopology: true,
}
)
.then(
() => {
console.log("mongoDB conneted");
},
(err) => {
console.log(err);
}
);
module.exports = connectDB;
user.js
const express = require("express");
const router = express.Router();
const mongoose = require("mongoose");
const bcrypt = require("bcrypt");
const jwt = require("jsonwebtoken");
const {body, validationResult} = require("express-validator");
router.get("/", (req, res) => {
res.send("hello");
});
router.post(
"/",
[
// password must be at least 5 chars long
body("email").isEmail(),
body("password").not().isEmpty(),
],
async (req, res) => {
const errors = validationResult(req);
if (!errors.isEmpty) {
return res.status(400).json({errors: errors.array()});
}
try {
const UsersSchema = mongoose.Schema({
email: {type: String, required: true},
password: {type: String, required: true},
});
var users = mongoose.model("user", UsersSchema);
var user = new users({
email: req.body.email,
password: req.body.password,
});
const salt = await bcrypt.genSalt(10);
user.password = await bcrypt.hash(req.body.password, salt);
user.save((err, user1) => {
if (err) {
console.log("error posing user");
throw err;
}
});
console.log(user.id);
const payload = {
user: {
id: user.id,
},
};
} catch (error) {
console.log(error);
res.status(400);
}
}
);
module.exports = router;

Answer 1

Every time the route runs it tries to create a schema which is already created.Mongoose create the collection with the first argument user by converting it to plural i.e. users.