Gaurish Sethia

Posted on Mar 6, 2023

Create a CRUD App with Bun and Elysia.js

In this article we will be creating a crud web application with Bun and Elysia.js

Before we start creating, Let's get to know about Bun?

What is Bun?

Bun is an incredibly fast JavaScript runtime, bundler, transpiler and package manager similar to Node.js and Deno . It has a lot of promising features (check them out on the Roadmap) and aims to replace Node.js. It was created by Jarred Sumner in Zig and uses JavaScript core instead of v8

The cool thing about this is it has built-in TypeScript support, Yes you no longer need tsc, Moreover you can write packages in Typescript and publish it to the NPM Registry as-is, Though your package will then be limited to Bun users.

The benchmarks can be seen on the website

Let's install Bun now,



curl -fsSL https://bun.sh/install | bash

Verify your install and let's dive into creating the web application.

Creating the Application

First of all, Create a new directory and change your path to it and then run the bun init command.

It will create a Typescript based new project, Now let's begin writing some code. Open the directory in your IDE (mine is VSCode).

You'll see something like this:

Now, Let's install our dependencies:

elysia - The web framework we're using.
@elysiajs/html - HTML Plugin for the web framework



bun a elysia @elysiajs/html

Now's let's create the backend first, We'll create an api which can be called from the frontend to store,retrieve,edit and delete books stored in SQLite Database (BTW, Bun provides the fastest SQLite in JavaScript ecosystem)

We create a db.ts to store the Database stuff which should look like this:



import { Database } from 'bun:sqlite';

export interface Book {
    id?: number;
    name: string;
    author: string;
}

export class BooksDatabase {
    private db: Database;

    constructor() {
        this.db = new Database('books.db');
        // Initialize the database
        this.init()
            .then(() => console.log('Database initialized'))
            .catch(console.error);
    }

    // Get all books
    async getBooks() {
        return this.db.query('SELECT * FROM books').all();
    }

    // Add a book
    async addBook(book: Book) {
        // q: Get id type safely 
        return this.db.query(`INSERT INTO books (name, author) VALUES (?, ?) RETURNING id`).get(book.name, book.author) as Book;
    }

    // Update a book
    async updateBook(id: number, book: Book) {
        return this.db.run(`UPDATE books SET name = '${book.name}', author = '${book.author}' WHERE id = ${id}`)
    }

    // Delete a book
    async deleteBook(id: number) {
        return this.db.run(`DELETE FROM books WHERE id = ${id}`)
    }

    // Initialize the database
    async init() {
        return this.db.run('CREATE TABLE IF NOT EXISTS books (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, author TEXT)');
    }
}

Here, We create a class BooksDatabase and create a Database instance in it, Add methods to create,retrieve,edit books and initialize the database (create tables).

What does each function do?

addBook - Creates a new book in the database and return the autoincremented id
getBooks - Get all the books in the database
updateBook - Update a existing book in the database
deleteBook - Delete a book from the database

Now, Let's begin creating the API, Elysia is a minimalistic web framework and does not require any extra knowledge, It is full of awesome features, Check out the available plugins here

We start with this:



import { Elysia } from 'elysia';
import { html } from '@elysiajs/html'
import { BooksDatabase } from './db.js';

new Elysia()
    .use(html())
    .decorate('db', new BooksDatabase())
    .listen(3000);

Create a new Elysia instance, Inject the html plugin and add a new db property which can accessed by our route handlers.

Now, let's start creating the routes

First, Let's create a index.html file which will contain our main site



<!DOCTYPE html>
<html>
    <head>
        <title>My Bookstore</title>
        <script src="/script.js"></script>
    </head>
    <body>
        <h1>My Bookstore</h1>
        <button onclick="addNewBook()" type="button">Add Book</button>
        <button onclick="deleteBook()" type="button">Remove Book</button>
        <button onclick="updateBook()" type="button">Update Book</button>
        <ul id="bookList"></ul>
    </body>
</html>

This is a simple overview of how the file will look, Make sure to add <!DOCTYPE html> in the starting of the file so that the html plugin can add the Content type header.

Now, moving back to our index.ts we create a route to serve this index.html. Elysia provides a static plugin as well which we won't use since we have only 2 static files.

Create a new GET route which will read index.html file and send the text



import { Elysia } from 'elysia';
import { html } from '@elysiajs/html'
import { BooksDatabase } from './db.js';

new Elysia()
    .use(html())
    .decorate('db', new BooksDatabase())
    .get("/", () => Bun.file("index.html").text())
    .listen(3000);

Create a script.js route and add a route for the same



import { Elysia } from 'elysia';
import { html } from '@elysiajs/html'
import { BooksDatabase } from './db.js';

new Elysia()
    .use(html())
    .decorate('db', new BooksDatabase())
    .get("/", () => Bun.file("index.html").text())
    .get("/script.js", () => Bun.file("script.js").text())
    .listen(3000);

Now, Let's create the database routes,



import { Elysia } from 'elysia';
import { html } from '@elysiajs/html'
import { BooksDatabase } from './db.js';

new Elysia()
    .use(html())
    .decorate('db', new BooksDatabase())
    .get("/", () => Bun.file("index.html").text())
    .get("/script.js", () => Bun.file("script.js").text())
    .get("/books", ({ db }) => db.getBooks())
    .listen(3000);

Notice the db autocomplete in the handler :)

Create routes for creating a book



import { Elysia, t } from 'elysia';
import { html } from '@elysiajs/html'
import { BooksDatabase } from './db.js';

new Elysia()
    .use(html())
    .decorate('db', new BooksDatabase())
    .get("/", () => Bun.file("index.html").text())
    .get("/script.js", () => Bun.file("script.js").text())
    .get("/books", ({ db }) => db.getBooks())
    .post(
        "/books",
        async ({ db, body }) => {
          console.log(body)
          const id = (await db.addBook(body)).id
          console.log(id)
          return { success: true, id };
        },
        {
          schema: {
            body: t.Object({
              name: t.String(),
              author: t.String(),
            }),
          },
        }
      )

    .listen(3000);

Notice the schema validation, Elysia provides schema validation out of the box powered by @sinclair/typebox, Read more about this here

Now, let's create the remaining delete and put routes

After which your file should look like this:



import { Elysia, t } from "elysia";
import { BooksDatabase } from "./db.js";
import { html } from '@elysiajs/html'

new Elysia()
  .use(html())
  .decorate("db", new BooksDatabase())
  .get("/", () => Bun.file("index.html").text())
  .get("/script.js", () => Bun.file("script.js").text())
  .get("/books", ({ db }) => db.getBooks())
  .post(
    "/books",
    async ({ db, body }) => {
      const id = (await db.addBook(body)).id
      return { success: true, id };
    },
    {
      schema: {
        body: t.Object({
          name: t.String(),
          author: t.String(),
        }),
      },
    }
  )
  .put(
    "/books/:id",
    ({ db, params, body }) => {
      try {
        db.updateBook(parseInt(params.id), body) 
        return { success: true };
      } catch (e) {
        return { success: false };
      }
    },
    {
      schema: {
        body: t.Object({
          name: t.String(),
          author: t.String(),
        }),
      },
    }
  )
  .delete("/books/:id", ({ db, params }) => {
    try {
      db.deleteBook(parseInt(params.id))
      return { success: true };
    } catch (e) {
      return { success: false };
    }
  })
  .listen(3000);

Let's create the script.js now:



window.addEventListener("DOMContentLoaded", function () {
    fetch("/books", {
        method: "GET",
        headers: {
            "Content-Type": "application/json"
        }

    })
        .then((res) => res.json())
        .then((books) => {
            document.getElementById("bookList").innerHTML = books.map((book) => {
                return `
                <li id="${book.id}">
                    ID: ${book.id} <br> Name: ${book.name} <br> Author: ${book.author}
                </li>
            `
            }).join("");
        })
}, false);

Whenever the page is loaded, Fetch the books and add them to the unordered list

Create the new addNewBook function which prompts the user for book name and author then makes the request to api to save it in the database



const addNewBook = () => {
    const newBook = prompt("Book name & author (separated by a comma)");
    if (newBook) {
        const [name, author] = newBook.split(",");
        fetch("/books", {
            method: "POST",
            headers: {
                "Content-Type": "application/json",
            },
            body: JSON.stringify({ name, author }),
        })
            .then((res) => res.json())
            .then((res) => {
                if (res.success) {
                    document.getElementById("bookList").innerHTML += `
                    <li id="${res.id}">
                        ID: ${res.id} Name: ${name} <br> Author: ${author}
                    </li>
                `
                }
            });
    }
};

Create the remaining functions updateBook deleteBook



const deleteBook = () => {
    const bookPrompt = prompt("Book ID");
    if (!bookPrompt) return alert("Invalid book ID");
    const bookId = parseInt(bookPrompt);
    if (bookId) {
        fetch(`/books/${bookId}`, {
            method: "DELETE",
        })
            .then((res) => res.json())
            .then((res) => {
                if (res.success) {
                    document.getElementById(bookId).remove();
                }
            });
    }
};

const updateBook = () => {
    const bookPrompt = prompt("Book ID");
    if (!bookPrompt) return alert("Invalid book ID");
    const bookId = parseInt(bookPrompt);
    if (bookId) {
        const newBook = prompt("Book name & author (separated by a comma)");
        if (newBook) {
            const [name, author] = newBook.split(",");
            fetch(`/books/${bookId}`, {
                method: "PUT",
                headers: {
                    "Content-Type": "application/json",
                },
                body: JSON.stringify({ name, author }),
            })
                .then((res) => res.json())
                .then((res) => {
                    if (res.success) {
                        document.getElementById(bookId).innerHTML = `
                        ID: ${bookId} <br> Name: ${name} <br> Author: ${author}
                    `
                    }
                });
        }
    }
};

After all this, Your file should look like this



window.addEventListener("DOMContentLoaded", function () {
    fetch("/books", {
        method: "GET",
        headers: {
            "Content-Type": "application/json"
        }

    })
        .then((res) => res.json())
        .then((books) => {
            document.getElementById("bookList").innerHTML = books.map((book) => {
                return `
                <li id="${book.id}">
                    ID: ${book.id} <br> Name: ${book.name} <br> Author: ${book.author}
                </li>
            `
            }).join("");
        })
}, false);

const addNewBook = () => {
    const newBook = prompt("Book name & author (separated by a comma)");
    if (newBook) {
        const [name, author] = newBook.split(",");
        fetch("/books", {
            method: "POST",
            headers: {
                "Content-Type": "application/json",
            },
            body: JSON.stringify({ name, author }),
        })
            .then((res) => res.json())
            .then((res) => {
                if (res.success) {
                    document.getElementById("bookList").innerHTML += `
                    <li id="${res.id}">
                        ID: ${res.id} Name: ${name} <br> Author: ${author}
                    </li>
                `
                }
            });
    }
};

const deleteBook = () => {
    const bookPrompt = prompt("Book ID");
    if (!bookPrompt) return alert("Invalid book ID");
    const bookId = parseInt(bookPrompt);
    if (bookId) {
        fetch(`/books/${bookId}`, {
            method: "DELETE",
        })
            .then((res) => res.json())
            .then((res) => {
                if (res.success) {
                    document.getElementById(bookId).remove();
                }
            });
    }
};

const updateBook = () => {
    const bookPrompt = prompt("Book ID");
    if (!bookPrompt) return alert("Invalid book ID");
    const bookId = parseInt(bookPrompt);
    if (bookId) {
        const newBook = prompt("Book name & author (separated by a comma)");
        if (newBook) {
            const [name, author] = newBook.split(",");
            fetch(`/books/${bookId}`, {
                method: "PUT",
                headers: {
                    "Content-Type": "application/json",
                },
                body: JSON.stringify({ name, author }),
            })
                .then((res) => res.json())
                .then((res) => {
                    if (res.success) {
                        document.getElementById(bookId).innerHTML = `
                        ID: ${bookId} <br> Name: ${name} <br> Author: ${author}
                    `
                    }
                });
        }
    }
};

Time to experiment the api, Start the server using bun index.ts It should log Database initialized and create the books.db file

Head to localhost:3000

This is what you should see:

How to use it?

Make sure to drop me a follow on twitter @gaurishhs

Get the github repo here:

gaurishhs / bun-web-app

Web application using Elysia and Bun

bun-web-app

To install dependencies:

bun install

To run:

bun run index.ts

This project was created using bun init in bun v0.5.7. Bun is a fast all-in-one JavaScript runtime.

View on GitHub

Top comments (3)

Nurul Abrar • Sep 2 '23

Really helped.
Can you integrate a session management system for users with elyysiajs and mongoose?
It would be very nice, with jwt token i can do that, but for session i am unable to do that.

I want to do something like create session like express-js and store session value in mongodb using connect-mongo and manage that.

Gaurish Sethia • Oct 19 '23

Hi!
First of all i'm happy that this helped you.
I just released a session management plugin for elysia here. This way you can integrate any database you want to easily.

Thanks!

kyoukhana • Jan 6

Now, Let's create the database routes, Would be a good idea to separate routes database and front-end.

DEV Community

Create a CRUD App with Bun and Elysia.js

What is Bun?

Creating the Application

gaurishhs / bun-web-app

Web application using Elysia and Bun

bun-web-app

Top comments (3)

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