A Feathers hook to remap service.create to do an upsert

hook.map-create-to-upsert.js

module.exports = function (upsertQuery) {
  if (typeof upsertQuery !== 'function') {
    console.warn('No `upsertQuery` function was passed to the mapCreateToUpsert hook. Please set params.upsertQuery in the hook context to dynamically declare the function.')
  }

  return function mapCreateToUpsert (context) {
    const { service, data, params } = context // const data = { address: '123', identifier: 'my-identifier' }

    upsertQuery = params.upsertQuery || upsertQuery
    if (typeof upsertQuery !== 'function') {
      throw new Error('you must pass a `upsertQuery` function to the mapCreateToUpsert hook in the options or as `params.upsertQuery` in the hook context')
    }

    params.mongoose = Object.assign({}, params.mongoose, { upsert: true })
    params.query = upsertQuery(context) // { address: '123' }

    return service.patch(null, data, params)
      .then(result => {
        context.result = result
        return context
      })
  }
}

using-the-hook.js

const mapCreateToUpsert = require('./hook.map-create-to-upsert')

app.service('my-service').hooks({
  before: {
    all: [],
    find: [],
    get: [],
    create: [
      mapCreateToUpsert(context => {
        const { data } = context
        return { address: data.address }
      })
    ],
    update: [],
    patch: [],
    remove: []
  }
})

The hook doesn't handle errors as expected if something goes wrong in upsertQuery(). This fixes the issues:

const logger = require('winston')

module.exports = function(upsertQuery) {
  if (typeof upsertQuery !== 'function') {
    logger.warn(
      'No `upsertQuery` function was passed to the mapCreateToUpsert hook. Please set params.upsertQuery in the hook context to dynamically declare the function.'
    )
  }

  return function upsert(context) {
    const { service, data, params } = context

    upsertQuery = params.upsertQuery || upsertQuery
    if (typeof upsertQuery !== 'function') {
      throw new Error(
        'You must pass a `upsertQuery` function to the mapCreateToUpsert hook in the options or as `params.upsertQuery` in the hook context'
      )
    }

    params.mongoose = Object.assign({}, params.mongoose, { upsert: true })
    
    try {
      params.query = upsertQuery(context)
    } catch (error) {
      context.error = error
      return context
    }

    return service
      .patch(null, data, params)
      .then(result => {
        delete context.error
        context.result = result
      })
      .catch(error => {
        context.error = error
      })
      .then(() => context)
  }
}