app.js

// =============== Requiring Express ====================
const express = require("express");
const morgan = require("morgan");
const bodyParser = require("body-parser");
const mongoose = require("mongoose");
const productROutes = require("./api/routes/products");
const orderRoutes = require("./api/routes/orders");
const userRoutes = require("./api/routes/user");
const { databaseUsername, databasePWD } = require("./config/config");

// ======================= Connecting to the Database ==================
mongoose.connect(
  "mongodb+srv://" +
    databaseUsername +
    ":" +
    databasePWD +
    "@protrasys-admin-raot8.mongodb.net/test?retryWrites=true&w=majority",
  { useUnifiedTopology: true, useNewUrlParser: true, useCreateIndex: true },
  err => {
    if (err) {
      console.log("Error is Occured ! + " + err);
    } else {
      console.log("DB Connected");
    }
  }
);

// =================== Executing express like a function =====================
const app = express();

app.use("/uploads", express.static("uploads"));

// ======================= Body Parser ===============================
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

// ====================== Logging Incoming Requests  ==========================
app.use(morgan("dev"));

// ======================= CORS Setup ===============================
app.use((req, res, next) => {
  res.header("Access-Control-Allow-Origin", "*");
  res.header(
    "Access-Control-Allow-Header",
    "Origin, X-Requested-With, Content-Type, Accept, Authorization"
  );
  if (req.method === "OPTIONS") {
    res.header("Access-Control-Allow-Methods", "GET,POST,PATCH,DELETE,PUT");
    return res.status(200).json({});
  }
  next();
});

// =================== Handling a request ================================
app.use("/products", productROutes);
app.use("/orders", orderRoutes);
app.use("/users", userRoutes);

app.use((req, res, next) => {
  const error = new Error("Not Found");
  error.status = 404;
  next(error);
});

app.use((error, req, res, next) => {
  res.status(error.status || 500);
  res.json({
    error: {
      message: error.message
    }
  });
});

// ===================== Exporting app =====================
module.exports = app;