Use facebook's dataloader to batch any Service get

feathersjs-dataloader.js

'use strict';

const DataLoader = require('dataloader');

class Service {
  constructor({ BaseService, options }) {
    this.id = BaseService.id || 'id';
    this.service = BaseService;

    this.dataloader = new DataLoader(this._batchGet.bind(this), options);
  }

  _batchGet(ids) {
    console.log('Batched Ids: ', ids.join(','));

    const cachedPromises = {};
    const promises = ids.map((id) => {
      if (cachedPromises[id] === undefined) {
        cachedPromises[id] = this.service.get(id);
      }
      return cachedPromises[id];
    });

    return Promise.all(promises);
  }

  find(params) {
    return this.service.find(params)
      .then((result) => {
        if (Array.isArray(result)) {
          result.forEach((object) => {
            this.dataloader.prime(object[this.id], object);
          });
        }

        return result;
      });
  }

  get(id, params) {
    return this.dataloader.load(id);
  }

  create(data, params) {
    if(Array.isArray(data)) {
      return Promise.all(data.map(current => this.create(current)));
    }

    return this.service.create(data, params)
      .then((object) => {
        this.dataloader.prime(object[this.id], object);
        return object;
      });
  }

  update(id, data, params) {
    return this.service.update(id, data, params)
      .then((object) => {
        this.dataloader.clear(id).prime(id, object);
        return object;
      });
  }

  patch(id, data, params) {
    return this.service.patch(id, data, params)
      .then((object) => {
        this.dataloader.clear(id).prime(id, object);
        return object;
      });
  }

  remove(id, params) {
    return this.service.remove(id, params)
      .then((object) => {
        this.dataloader.clear(id);
        return object;
      });
  }
}

function initService(options) {
  return new Service(options);
}

module.exports = initService;
module.exports.Service = Service;