middleware.md

Middleware Support

You can add Express-style middleware to both Routers and Endpoints in this framework. Middleware functions allow you to run logic before your endpoint handler is called (for example, authentication, logging, validation, etc.).

Router Middleware

To add middleware to a router, set the middleware property to an array of Express middleware functions. These will run for all endpoints registered under that router.

import { BaseApiRouter } from 'src/router/router';
import { RequestHandler } from 'express';

const logMiddleware: RequestHandler = (req, res, next) => {
  console.log('Request:', req.method, req.path);
  next();
};

export class MyRouter extends BaseApiRouter {
  override path = '/api';
  override middleware = [logMiddleware];

  async routes() {
    return [/* your endpoints */];
  }
}

Endpoint Middleware

To add middleware to a specific endpoint, set the middleware property to an array of Express middleware functions on your endpoint class. These will run only for that endpoint, after any router-level middleware.

import { BaseApiEndpoint, EndpointMethod } from 'src/router/endpoint';
import { RequestHandler } from 'express';

const authMiddleware: RequestHandler = (req, res, next) => {
  if (req.headers['authorization'] === 'Bearer validtoken') {
    next();
  } else {
    res.status(401).json({ error: 'Unauthorized' });
  }
};

export class MyEndpoint extends BaseApiEndpoint {
  override path = '/secure';
  override method = EndpointMethod.GET;

  override middleware = [authMiddleware];
  
  async handle(req, res) {
    return { ok: true };
  }
}

Middleware Order

• Router middleware runs first (in the order defined in the array).
• Endpoint middleware runs next (in the order defined in the array).
• Finally, the endpoint handler is called.

If any middleware sends a response (e.g., for authentication failure), the endpoint handler will not be called.

Example Use Cases

• Authentication/authorization
• Logging
• Input validation
• Rate limiting

See Also

• Express Middleware Documentation