cacheService.js

import NodeCache from 'node-cache'; // or 'redis'

class CacheService {

  constructor(ttlSeconds) {
    // this could also be redis
    this.cache = new NodeCache({ stdTTL: ttlSeconds, checkperiod: ttlSeconds * 0.2, useClones: false });
  }

  get(key, storeFunction) {
    const value = this.cache.get(key);
    if (value) {
      return Promise.resolve(value);
    }

    return storeFunction().then((result) => {
      this.cache.set(key, result);
      return result;
    });
  }
}


export default CacheService;

dataService.js

import DB from '../db';
import CacheService from '../cache.service';

const ttl = 60 * 60 * 1; // cache for 1 Hour
const cache = new CacheService(ttl); // Create a new cache service instance

const DataService = {
  // ...

  getDocsById(docID) {
    const selectQuery = `SELECT * FROM table WHERE docID = ${docID}`;

    return cache.get(docID, () => DB.then((connection) =>
      connection.query(selectQuery).then((rows) => {
        return rows[0];
      })
    )).then((result) => {
      return result;
    });
  }
}