Proposal: Hemera.add should throw BusinessError if promise-based handler rejects about hemera HOT 7 CLOSED

In the example above asCallback is from https://www.npmjs.com/package/ascallback

from hemera.

If I understand your case correctly you want to support to pass promises to callback handler or return them inside a normal function?

When yes this is definitely wrong because there are only two types of asynchronous composition which are very common in javascript.

• Callback style

  hemera.add({
    topic: 'test',
    cmd: 'boom',
    fail: Joi.boolean().required(),
  }, function (req, cb) {
    cb(<error>, <result>) // result can be any value, error must be an instance of Error
  })

• Async / Await

  hemera.add({
    topic: 'test',
    cmd: 'boom',
    fail: Joi.boolean().required(),
  }, async function (req, cb) {
    const result = await Promise.resolve()
    return result // can be a promise or any other value
  })

• Pass promise as value

Some others support this syntax but we don't provide a reply interface in an act or add

  hemera.add({
    topic: 'test',
    cmd: 'boom',
    fail: Joi.boolean().required(),
  }, async function (req, reply) {
       reply.send(Promise.resolve())
  })

This is possible in hemera.

      hemera
        .act(
          {
            topic: 'math',
            cmd: 'add',
            a: 1,
            b: 2
          })
          .then(..)
          .catch(..)

Could I answer your question?

from hemera.

You have to decide between callback or async / await don't mix them.

from hemera.

Yep, if you want to use promises with hemera, return an async function or use asCallback.

from hemera.

Could I answer your question?

from hemera.

Yes, I believe so. Thanks.

I've always been under the impression that (from the callers perspective) both of the following just return a promise. I guess there are some subtleties that I haven't ran into until now.

async () => {
  return await myPromise()
}

() => {
  return myPromise()
}

from hemera.

No, this is quite uncommon.

from hemera.