A feathers.js before create hook to handle Mongoose upserts

feathers-upsert-before-create-hook.js

// Use this hook to manipulate incoming or outgoing data.
// For more information on hooks see: http://docs.feathersjs.com/hooks/readme.html
import fromPairs from 'lodash/fromPairs'
import map from 'lodash/map'

/**
* upsert
* Executes upsert on a Mongoose model
* Configure in your service as a before:create hook
* Note: Update hooks will not fire as a result
* @arg {String} serviceName The feathers service name
* @arg {Array} keyNames The model key field names
* @return {Promise} The resolved hook
*/
module.exports = function (serviceName, keyNames) {
  return function (hook) {
    const service = hook.app.service(serviceName)

    const pairs = keyNames.map((field) => ({
      key: field,
      val: hook.data[field]
    }))

    const query = fromPairs(map(pairs, i => [i.key, i.val]))

    return service.Model.findOneAndUpdate(query,
      { $set: hook.data }, {
        new: true,
        upsert: true
      }).exec().then((res) => {
        hook.result = res

        return hook
      })
  }
}