APIs

Any file ends with .ts, .js, and .mjs inside the api/ directory is mapped to /api/* and will be treated as an API endpoint. For an API to work, you need to export a function as default or named to handler, that has the context object (instance of APIContext) as the first parameter.

For example, the following API route api/user.ts sends a json response when you visit /api/user.

import type { APIHandler } from 'https://deno.land/x/aleph/types.d.ts'

export const handler: APIHandler = ({ response }) => {
  response.json({ name: 'Aleph' })
}

Dynamic API Routes

Aleph.js supports dynamic API routes as well. For example, the route api/user/[name].ts has the following code:

import type { APIHandler } from 'https://deno.land/x/aleph/types.d.ts'

export const handler: APIHandler = ({ response, router }) => {
  response.json({ name: router.params.name })
}

This route will handle all /api/user/:name requests and reply with a json response that has the name param.

APIContext Object

The APIContext object aligns to the Deno.RequestEvent as the first argument of the API handler or middleware.

interface APIContext extends Deno.RequestEvent {
  data: Map<string, any> // The data handled by middlewares.
  response: APIResponse  // An interface that aligns to the parts of the `Response` with helper methods
  router: RouterURL      // The router for the api routing.
}

type APIHandler = {
  (context: APIContext): Promise<void> | void
}
type APIMiddleware = {
  (context: APIContext, next: () => void): Promise<void> | void
}

Middlewares

In Aleph.js, a middleware for APIs is like APIHandler but with a next callback that calls next middleware or the final handler. You can have multiple middlewares that will be applied to all the API routes. To use middlewares add a _middlewares.ts in the api/ directory and ensure export a middlewares array as default.

// api/_middlewares.ts

import type { APIMiddleware } from 'https://deno.land/x/aleph/types.d.ts'

const data:APIMiddleware = ({ response, data }, next) => {
  response.headers.set('server', 'Aleph.js')
  data.set('foo', 'bar')
  next()
}

const auth:APIMiddleware = ({ response, data, request }, next) => {
  const token = request.header.get('Authorization')
  if (!token) {
    response.status = 401
    response.body = 'Unauthorized'
    return
  }

  const currentUser = auth(token)
  data.set('currentUser', currentUser)
  next()

  // log message at last
  console.log(response.headers.get('server'))
  console.log(data.get('foo'))
}

export default [data, auth]

As optional, you can also add global middlewares in aleph.config.ts those are put in front of api/_middlewares.ts defines:

import type { Config } from 'https://deno.land/x/aleph/types.d.ts'

export default <Config>{
  server: {
    middlewares: [
      ({ response, data }, next) => {
        response.headers.set('server', 'Aleph.js')
        data.set('foo', 'bar')
        next()
      }
    ]
  }
}