A middleware for automatically converting AdonisJS responses to JSONP

README.md

JsonpDetector middleware

A simplistic approach to automatically converting responses to JSONP, since Adonis does not do this for you.

Compatible with Adonis 4.1

Installing

1. adonis make:middleware JsonpDetector
2. In start/kernel.js, add App/Middleware/JsonpDetector as to the global middleware array.
3. In app/Middleware/JsonpDetector.js, replace the file with the file from this gist.

JsonpDetector.js

'use strict'

const Config = use('Config')

/**
 * JSON-P middleware for AdonisJS 4.1
 * https://gist.github.com/Sleavely/da1ac50e1ea614b4171beae7868ec3ed
 */
class JsonpDetector {
  async handle ({ request, response }, next) {

    // Run routes
    await next()
    // Okay, so now there should be a request ready to be sent.

    // Lets figure out if making it JSONP is relevant by making sure that:
    // - The JSONP callback parameter is set
    // - The user didnt use response.json() or response.jsonp()
    // - The content doesnt look like XML/HTML

    const queryParams = request.get()
    if(typeof queryParams[ Config.get('app.http.jsonpCallback') ] === 'undefined')
    {
      // No JSONP callback set
      return;
    }

    if(response.lazyBody.method != 'send')
    {
      // response.json() or response.jsonp() was used
      return;
    }

    if(typeof response.lazyBody.content == 'string')
    {
      // XML-like?
      if(response.lazyBody.content.trim().indexOf('<') === 0)
      {
        return;
      }
    }

    response.jsonp(response.lazyBody.content)
  }
}

module.exports = JsonpDetector