server.js

const express = require("express");
const mongoose = require("mongoose");
const cors = require("cors");
const passport = require("passport");

require("dotenv").config();

const app = express();
const port = process.env.PORT || 5000;

app.use(cors());
app.use(express.json());
app.use(passport.initialize());

const uri = process.env.MONGODB_URI;
// current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
mongoose.connect(uri, {
  useUnifiedTopology: true,
  useNewUrlParser: true,
  useCreateIndex: true,
});

const connection = mongoose.connection;

connection.once("open", () => {
  console.log("*** MongoDB database connection established successfully ***");
});

const exerciseRouter = require("./routes/exercises");
const userRouter = require("./routes/users");

app.use("/exercises", exerciseRouter);
app.use("/users", userRouter);

app.get("/", (req, res) => {
  res.json({ message: `Server is running on port: ${port}` });
});

app.listen(port, () => {
  console.log(`Server is running on port: ${port}`);
});