Connecting To MongoDB

Now that we have our cloud database hooked up to our application, we need to connect to it. We'll use the Mongoose library to do this.

Installing Mongoose & dotenv

We are actually going to install two packages right now. One is Mongoose, which is called an "ODM" or "Object Document Mapper". This is a library that allows us to connect to our MongoDB database and interact with it. The other is called dotenv, which is a library that allows us to store environment variables in a file called .env. We'll use this to store our MongoDB connection string.

npm install mongoose dotenv

.env Setup

Let's add our MongoDB connection string as an environment variable. Create a file called .env in your root folder. Add the connection string that you copied from MongoDB Atlas in the last lesson. It should look something like this:

MONGODB_URI=mongodb+srv://<username>:<password>@cluster0-0z0z0.mongodb.net/ideas_db?retryWrites=true

I also add my port here. I'm going to use port 5000. You can use whatever port you want.

PORT=5000

Now, in the server.js file, we need to require the dotenv package and call the config method. This will load the environment variables from the .env file.

require('dotenv').config();

Now, I will create a variable called PORT and set it to the value of the PORT environment variable. If it doesn't exist, I will set it to 5000. Then, just use that in the app.listen method.

const PORT = process.env.PORT || 5000;
app.listen(PORT, () => {
  console.log(`Server is listening on port ${PORT}`);
});

Connecting To MongoDB

Now, let's connect to MongoDB. We'll use the Mongoose library to do this. Instead of putting this code directly in the server.js file, I'm going to create a folder called config and in it, create a new file called db.js. This will be a separate file that will handle all of our database connection logic.

const mongoose = require('mongoose');

const connectDB = async () => {
  const conn = await mongoose.connect(process.env.MONGODB_URI);
  console.log(`MongoDB Connected: ${conn.connection.host}`);
};

mongoose.set('strictQuery', true);

module.exports = connectDB;

Now, in the server.js file, we need to require the connectDB function and call it.

const connectDB = require('./config/db');

connectDB();

Now when you start your server, you should see a message that says "MongoDB Connected".

Congrats, you've connected to your MongoDB database!