Creating a Login System with Koa Typescript, Objection.js, JWT, React, and MySQL

Jan 7 · 10 min read
koa typescript

In this tutorial, we are going to build a simple login using React for the frontend application and Koa(Typescript) for the backend application

Aside from React and Koa, we will be using Objection.js (ORM) and MySQL (database).


First, we need to make sure we already have Node.js installed.

Setting Up The Koa Backend App

Let’s first set up the backend application, then we will continue with the frontend, React.

We will be using Koa for our backend framework. Originally, Koa comes in Javascript but since Typescript has been getting a lot of attention, we will be using Typescript to set up Koa.

Run the following command.

The above install all the necessary node modules that we will need in our project for now.

Using Typescript for Koa

Since we will be using Typescript for Koa, we will need to create a tsconfig.json file.

Go ahead and create a tsconfig.json in your root folder, then paste the following in the file.

The above are pretty basics configurations for Typescript. You can read more about it here.


Now, to make things easier for us during development, we will need to use nodemon. There is a more neat way to use nodemon which is through using nodemon.json.

Create nodemon.json in your root folder and paste the following codes.

Now, go into your package.json and paste the followings replacing your "scripts".

Server File

After we have set up the tsconfig.json and nodemon.json, it is time to write codes for the Koa server.

Create a folder src and inside the folder create a new file and name it index.ts. Paste the following inside it.

Go ahead and run npm run dev and go to localhost:3500.

The above codes only run the basic Koa server. From here we will need to create controllers, models, routes, and DB config file.

Configuring Database

Let’s start with creating the config file to connect to our database (MySQL).

To make things easier for us, we will be using a type of ORM which is known as Objection.js

First, make sure you have installed it.

Objection.js is a Node.js ORM that is built on an SQL query builder known as knex.

With Objection.js, we can make our work easier. We can save a lot of time during development.

To use Objection.js, first create an knexfile.ts in the root folder. Make sure it is not in your src folder.

Paste the followings in your knexfile.ts.

Make sure you change the DB credentials accordingly.

Now that the knexfile.ts has been created, we need to import it in our index.ts to make the connection.

Open the index.ts and paste the following.

Now let’s move on to defining our Models.

Defining Models

Before we can proceed with the migrations and seeds, we need to define our models first.

Go ahead and a new folder in the src folder and name it models.

In the src/models/, create two new file name as User.ts and Book.ts.

In the User.ts, paste the following.

In the Book.ts, paste the following.

And that’s it for our models. We’ve created one Model for the User and another one for Book.

Migrations and Seeds

With Objection.js, we can run migrations and seeds easily. This helps us to version control our database and allow us to modify the database schema and stay up to date with the current schema.

Seeding allows us to populate our database with fake or dummy data which will allow us better insight during development.

To start, open package.json and paste the following.

We have added four new commands to the "scripts" which are make:migration, migrate, make:seed and seeding.

First, we need to have a migration file created and since we want to eliminate manual as much as possible, running make:migration will help us to create a new migration file.

Run make:migration and open the newly created file. Paste the following inside it.

As you can see, there are only two functions here up and down.

With up, you can specify the type of tables and the table’s columns that you want to create based on your models.

With down you can drop any existing table, this helps us to delete the old existing table and create a new one if there are any changes to the database schema.

Next up is seeding.

Again, to make things easier, run make:seed to help us automatically create a seed file.

Open the newly created seed file and paste the following.

The above I believed is fairly easy to understand. Just write any dummy data you want to dump into the table of your choice.

Run the above code would not actually create tables and populate them with fake data without YOU actually telling knex to do it.

Run migrate and seeding so that knex will do the manual work of creating tables and making rows for you.

Let’s move on with Controllers and Routes now.

Controllers and Routes

It is a good practice to group up all the controllers in one controller's folder.

Create a new folder at src/controllers and then create two new files src/controllers/book.controlller.ts and src/controllers/user.controller.ts.

Inside the book.controller.ts paste the following.

To explain the above code, we simply defined our routes in the controller file. One route for get and another one for post. You can define other method like patch or delete or even put depending on your preferences.

The above are just simple routes defined that are required in this project

Moving on to user.controller.ts. Inside the file, paste the following.

Inside the user.controller.ts, we defined only one route which is a post route that is used for login.

When the user logs into his/her account, we will send an HTTP request to the endpoint.

The endpoint in turn should validate the inputs and cross-check in the database before returning a token if the user exists in the database.

Return null if-else.

One last thing to do is to update the index.ts. Replace with the following.

And that’s it for our Koa backend application. If you try to send a request to the /book endpoint, you will get an error since you do not have the JSON web token or not authenticated.

Creating React Frontend

For a quick way to create a React app, run the following.

But since we used Typescript for the Koa backend, let’s use Typescript for React as well.

Run the following to create a React app Typescript.

Now, we are all set to start creating the necessary things for your Frontend application.

Creating Login and Profile Pages

We will be creating two pages namely Login and Profile.

The Login page should be public and the Profile page should be private or only accessible when you are authenticated.

Go ahead and create a new folder in the src folder and name it main.

Create two new files src/main/login.tsx and src/main/profile.tsx.

In the login.tsx, paste the following.

To explain what we coded in the login.tsx, the page contains a basic form which we will allow User to input their username and password.

Upon form submit, we will take both the username and password and usefetch method to make a POST request to our backend server at /login endpoint.

Once our backend server complete the process, it will return the token which our frontend will obtain and save into the localStorage through the setToken method.

But where does the setToken method comes from? We will talk about it after we finish the profile page.

In the profile.tsx, paste the following.

In profile.tsx, we will use fetch to send a get HTTP request to a protected route in our backend server. Simple stuff.

We are almost done with our frontend app, with only two things left to do. To create a service and modify our app.tsx

Creating A Service file for localStorage

Go ahead and create a file src/services/useToken.tsx, in the file paste the following.

This is a service that we will use later to set and get our item in the localStorage.

And now finally, open the app.tsx and paste the following.

On a side note, there are many ways that you can build the same process. What I’ve shown above is one way that I did and if you think you can improve it to be better, then let’s have a knowledge sharing to improve our knowledge.

And with that, authentication should now work between the React frontend and the Koa backend.

The End…


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