@alt-javascript/boot-koa

Koa adapter for the @alt-javascript framework. Bridges CDI-managed controllers to Koa routes with a built-in JSON body parser and CDI middleware pipeline.

Part of the @alt-javascript monorepo.

Install

npm install @alt-javascript/boot-koa koa

Usage

import { Boot } from '@alt-javascript/boot';
import { Context, Singleton } from '@alt-javascript/cdi';
import { koaStarter } from '@alt-javascript/boot-koa';

class TodoController {
  static __routes = [
    { method: 'GET',  path: '/todos',     handler: 'list'   },
    { method: 'POST', path: '/todos',     handler: 'create' },
    { method: 'GET',  path: '/todos/:id', handler: 'get'    },
  ];

  constructor() { this.todoService = null; } // autowired

  async list(request)   { return this.todoService.findAll(); }
  async create(request) { return this.todoService.create(request.body); }
  async get(request)    { return this.todoService.findById(request.params.id); }
}

const context = new Context([
  ...koaStarter(),
  new Singleton(TodoService),
  new Singleton(TodoController),
]);

await Boot.boot({ contexts: [context] });

Controllers receive a normalised request object { params, query, headers, body, ctx, koaCtx }. The built-in JSON body parser handles application/json content — no need for koa-bodyparser. The CDI context is available as koaCtx.cdiContext.

Middleware Pipeline

koaStarter() registers three built-in middleware components automatically:

| Component | Order | Behaviour | |---|---|---| | RequestLoggerMiddleware | 10 | Logs [METHOD] /path → status (Xms) | | ErrorHandlerMiddleware | 20 | Converts thrown errors to JSON error responses | | NotFoundMiddleware | 30 | Returns 404 for unmatched routes |

Add custom middleware by declaring static __middleware = { order: N }:

class AuthMiddleware {
  static __middleware = { order: 5 };

  async handle(request, next) {
    const token = request.headers.authorization?.replace('Bearer ', '');
    if (!token) return { statusCode: 401, body: { error: 'Unauthorized' } };
    return next({ ...request, user: { token } });
  }
}

Configuration

| Key | Default | Description | |---|---|---| | server.port | 3000 | Port to listen on | | server.host | 0.0.0.0 | Host to bind | | middleware.requestLogger.enabled | true | Enable request logging | | middleware.errorHandler.enabled | true | Enable error handler | | middleware.notFound.enabled | true | Enable 404 handler |

License

MIT