server.js

require('dotenv').config();
const express = require("express");
const mongoose = require("mongoose");
const bodyParser = require("body-parser");
const passport = require("passport");
const path = require("path");

const users = require("./routes/users");
const books = require("./routes/books");

const app = express();

app.use(
  bodyParser.urlencoded({
    extended: false
  })
);
app.use(bodyParser.json());
app.use(express.static(path.join(__dirname, "client/build")));

const db = require("./config/keys").ATLAS_URI;

mongoose.set('useFindAndModify', false);
mongoose.connect(db, { useNewUrlParser: true, useUnifiedTopology: true })
  .then(() => console.log("MongoDB successfully connected"))
  .catch(err => console.log(err));

app.use(passport.initialize());

require("./config/passport")(passport);

app.use("/users", users);
app.use("/books", books);

if (process.env.NODE_ENV === "production") {
  app.use(express.static("client/build"));

  app.get("*", (req, res) => {
    res.sendFile(path.resolve(__dirname, "client", "build", "index.html"));
  });
}

const port = process.env.PORT || 5000;

app.listen(port, () => console.log(`Server up and running on port ${port} !`));