Node module for Redis hmsetex command

hmsetex.js

/**
* npm install --save lodash redis node-redis-scripty
*
* Usage:
*   let hmsetex = require('./hmsetex.js')
*   let key = 'your-key';
*   let fields = { some_field: 'test', another_field: 'foo' };
*   hmsetex(key, fields).then(handleResult).catch(handleError);
*/
const _ = require('lodash');
let Scripty = require('node-redis-scripty');
let redis = require('redis');
let yourRedisClient = redis.createClient();
let scripty = new Scripty(yourRedisClient);

const hmsetexsrc = `
  local key = KEYS[1]
  local args = ARGV
  local call = redis.call

  if call("EXISTS", key) == 0 then
    return nil
  end

  return call("HMSET", key, unpack(args))
`;

module.exports = function(key, fields) {
  return new Promise((resolve, reject) => {
    scripty.loadScript('hmsetex', hmsetexsrc, (err, script) => {
      if (err) return reject(err);

      // Make sure any null values are set to '' for redis
      Object.keys(fields).forEach(k => {
        if (fields[k] === null) fields[k] = '';
      });

      let args = _.flatten(_.toPairs(fields));
      let numKeys = 1;
      script.run(numKeys, key, ...args, (err, result) => err ? reject(err) : resolve(result));
    });
  });
};