Middleware example: a custom response for login requests

Probably the most simple way to create a custom response is to create a quick middleware plugin.

Simple plugin to demonstrate handling a login request:

class Example {
  middleware (config) {
    return async (ctx, next) => {
      if (ctx.request.path === '/login' && ctx.request.method === 'POST') {
        const { username, password } = ctx.request.body
        if (password === '123') {
          ctx.response.body = `Welcome ${username}`
        } else {
          ctx.response.body = `Wrong password`
        }
      }
      await next()
    }
  }
}

export default Example

Save it to example.js then launch a server. The order of middleware plugins passed to --stack is significant - in this example, lws-body-parser is included before example.js - this ensures the request body has been parsed and made available on ctx.request.body before the example middleware is invoked.

$ ws --stack lws-log lws-body-parser tmp/example.js -f dev

Make some test requests..

$ curl http://127.0.0.1:8000/login -d '{ "username": "Lloyd" }' -H 'content-type: application/json'
Wrong password

$ curl http://127.0.0.1:8000/login -d '{ "username": "Lloyd", "password": "123" }' -H 'content-type: application/json'
Welcome Lloyd