Asychronous processing in Node is often heavily used, especially when database operations or external API data need to be cached.

Luckily there's an handy wrapPromise included in this hook to easily handle this for you.

• key [String] The key this item will be cached under within Redis.

• Promise A deferred promise. The return value of this will be the cached data.

• TTL

  • default: 60 How long the item will be stored in Redis.

The key thing to remember with this is to always return a deferred promise, otherwise it'll still execute the promise each time as in in-line function.

const deferred = () => {
  return new Promise(resolve => { 
    // Simulate a long async task
    setTimeout(() => {
      return resolve('some mocked api data');
    }, 3000);
  });
};

return Cache
  .wrapPromise(
    'external-api-data',
    deferred,
    120
  );

In this example, the deferred promise will only execute once per 2 minutes.

Functions which also return a promise, such as database queries using the Waterline ORM can be passed in directly, which has the same effect:

const deferred = () => {
  return User.find();
};

return Cache
  .wrapPromise(
    'external-api-data',
    deferred,
    120
  );