addParamsForward.js

/*
  Install this hook in app.hooks.js
  
  module.exports = app => {
    app.hooks({
      before: {
        all: [
          addParamsForward()
        ]
      }
    })
  }
  
  Then use whenever you want to forward params, e.g. in a hook:
  
  const { app, params } = context
  app.service('another-service').find({ query: { id: 'x' }, ...params.forward() })
  app.service('another-service').get(id, params.forward())
  app.service('another-service').patch(id, {smth: 'x' }, params.forward())
*/

const { has } = require('lodash')
const paramsSeen = new WeakSet()

module.exports = function addParamsForward() {
  return context => {
    if (paramsSeen.has(context.params)) {
      throw new Error(
        `Params should never be shared across services, always use params.forward(). Fix calls to ${context.path}#${context.method}`,
      )
    }

    paramsSeen.add(context.params)

    context.params.forward = ({ only, omit = [] } = {}) => {
      const { params } = context

      const forwardedParams = {
        caller: {
          path: context.path,
          method: context.method,
          type: context.type,
        },
        requestId: context.params.requestId,
        forwarded: true,
      }

      ;(
        only || [
          'authenticated',
          'user',
          'transaction',
          'skipEvents',
          'permissions',
        ]
      ).forEach(param => {
        if (has(params, param) && !omit.includes(param)) {
          forwardedParams[param] = params[param]
        }
      })

      if (forwardedParams.authenticated) {
        forwardedParams.authentication = params.authentication
      }

      return forwardedParams
    }
  }
}

@bwgjoseph you're right, it could be fixed by readding addParamsForward() hook in after all, so that it uses updated the closed over context when computing forwardedParams.