Koa

Install Required Packages

To set up your Koa server with Remult, run the following commands to install the necessary packages:

npm install koa koa-bodyparser remult
npm install --save-dev @types/koa @types/koa-bodyparser tsx

Bootstrap Remult in the Backend

Remult is integrated into your backend as middleware for Koa.

1. Create the API File

   Create a new api.ts file in the src/server/ folder with the following code to set up the Remult middleware:

   // src/server/api.ts
   
   import { createRemultServer } from 'remult/server'
   
   export const api = createRemultServer()

2. Register the Middleware

   Update the index.ts file in your src/server/ folder to include the Remult middleware. Add the following lines:

   // src/server/index.ts
   
   import * as koa from 'koa'
   import * as bodyParser from 'koa-bodyparser'
   import { api } from './api.js'
   
   const app = new koa()
   
   app.use(bodyParser()) // Enables JSON body parsing for API requests
   
   app.use(async (ctx, next) => {
     const r = await api.handle(ctx.request) // Handle API requests with Remult
     if (r) {
       ctx.response.body = r.data
       ctx.response.status = r.statusCode
     } else {
       await next() // If not handled by Remult, pass on to the next middleware
     }
   })
   
   app.listen(3002, () => {
     console.log('Server started on port 3002')
   })

   ESM Configuration

   In this tutorial, we are using ECMAScript modules (esm) for the Node.js server. When importing files, you must include the .js suffix (as shown in the import { api } from "./api.js" statement).

   Additionally, make sure to set "type": "module" in your package.json file.

Create the Server's TypeScript Configuration

In the root folder, create a TypeScript configuration file named tsconfig.server.json to manage the server's settings:

{
  "compilerOptions": {
    "experimentalDecorators": true,
    "skipLibCheck": true,
    "esModuleInterop": true,
    "outDir": "dist",
    "rootDir": "src",
    "module": "nodenext"
  },
  "include": ["src/server/**/*", "src/shared/**/*"]
}

This configuration enables TypeScript decorators, ensures compatibility with ECMAScript modules, and specifies the file paths for the server and shared code.

Create an npm Script to Start the API Server

To simplify the development process, add a new script in your package.json file to start the Koa server in development mode:

// package.json

"dev-node": "tsx watch --env-file=.env --tsconfig tsconfig.server.json src/server"

• tsx: A TypeScript Node.js execution environment that watches for file changes and automatically restarts the server on each save.
• --env-file=.env: Ensures environment variables are loaded from the .env file.
• --tsconfig tsconfig.server.json: Specifies the TypeScript configuration file for the server.

Start the Koa Server

Finally, open a new terminal and run the following command to start the development server:

npm run dev-node

The server will now run on port 3002. tsx will watch for any file changes, automatically restarting the server whenever updates are made.