Koa Js : Part 3 - Connect a NoSQL database to your Koa server

Before you start, If you have no experience with Koa, make sure you've read part 1 of this tutorial.

In this part, we'll be starting from where we left off in part 1 so if you want to follow along clone this repository but creating a NoSQL database instead. To do this we'll be using MongoDB.

Before we start let's make sure we have MongoDB installed.

Run the following command:

mongod --version

If it's installed, let's proceed.

Setup

MongoDB is non-relational database, meaning each object we post into our database does not need to have the same keys. But mongoose allows us to set up schemas which makes our types more strict.

In this tutorial we will be using Mongoose. So let's start by installing Mongoose:

npm i mongoose

Models

Once mongoose is installed let's create our models folder and our first model and called it event.models.js.

So let's run the following commands:

mkdir models
touch models/index.js
touch models/event.models.js

These commands will create a folder with two files named index.js and event.models.js.

Let's first add the following code to index.js:

const mongoose = require('mongoose');

const settings = {
    useNewUrlParser: true,
    useUnifiedTopology: true 
}

mongoose.connect("mongodb://localhost:27017/database", settings);

module.exports = mongoose;

This file will connect us to our mongoDB database.

Create our first model

Now let's add the following to event.models.js:

const { Schema, model } = require('.');

const eventsSchema = new Schema({
    attendees: Number,
    name: String,
    adultsOnly: Boolean,
    description: String,
    organizers: String
});

const Events = model('Events', eventsSchema);

module.exports = Events;

These are the types we've just created:

1. Name - this will be a string representing the name of the event.
2. Adults Only - this will be a boolean field.
3. Attendees - this will be a number representing the number of attendees.
4. Description - this will also be a string field.

Controllers

Let's import the model we just created into our controllers file.

const events = require('../models/events');

Post Request

Let's now update our post request in our event.controllers.js

The post request takes the request body and creates an object in our mongo database.

• A successful request will return 'Event Created!',
• An unsuccessful request will return a status 500 error.

const postEvent = async ctx => {
    try {
        await Events.create(ctx.request.body);
        ctx.body = 'Event Created!'
        ctx.status = 201;
    } catch (e) {
        console.log(err)
        ctx.status = 500
        throw(err)
    }
};

Try posting an item to the following endpoint on postman http://127.0.0.1:8000/post_event:

Let's move on to the get request!

Get Request

Let's also update our get request in our event.controllers.js.

We need to update our function to make it async and returns all the event items stored in our Mongo database.

const getEvents = async ctx => {
    try {
        const results = await Events.find()
        ctx.body = results
        ctx.status = 200
    } catch (err) {
        console.log(err)
        ctx.status = 500
        throw(err)
    }
}

Try posting an item to the following endpoint on postman http://127.0.0.1:8000/events_list:

If this works correctly you should get the following:

[
    {
        "_id": "RANDOM GENERATED ID",
        "attendees": 100,
        "name": "test event",
        "adultsOnly": false,
        "description": "test event description",
        "__v": 0
    }
]

And that's all she wrote! A mongoDB database with Koa Js, quick and painless. Here is the repo.

Comments

[Andrew Baisden]

All of these Node backend share so many similarities because they are based on express. It makes it easy to switch between them. Already have familiarity with express and Nest.js.

[Kachi Cheong]

Yes exactly. Actually Koa Js was designed by the team behind Express with the aim to make it smaller and more expressive. Which makes it perfect for more lightweight projects.