src/createResponderMiddleware.js

/**
 * Creates an Express middleware that responds to the request with either the requested data or the error. It only
 * handles requests that have passed through `createModelMiddleware`, and will forward other requests to the next
 * middleware
 * @returns {function[]} The Express middleware.
 * @example
 * app.use(createResponderMiddleware())
 */
export default function createResponderMiddleware() {
  return [
    (req, res, next) => sendResponse(null, req, res, next),
    (error, req, res, next) => sendResponse(error, req, res, next),
  ]

  function sendResponse(error, req, res, next) {
    if (!res.autonym) {
      next(error)
      return
    }

    res.status(res.autonym.getStatus())
    const data = res.autonym.getData()
    if (data === null) {
      res.end()
    } else {
      res.json(data)
    }

    next(error)
  }
}