RSVP doesn't work right with 'await'

[boris-petrov]

I've been struggling with an issue we have for the past few days. It seems to go away when I don't use await with RSVP.all/hash. I still cannot create a reproduction (will post it here if I manage) but we do something like:

class Foo
  constructor: ->
    @loading = {}
    @loading.c = @find()
    @wait()

  findHelper: (properties) ->
    result = for property in properties
      promise = new Ember.RSVP.Promise (resolve) ->
        setTimeout ->
          resolve()
        , 2000
      @loading[property] = promise.then ->
        console.log 'resolved'
    Ember.RSVP.all(result)

  find: ->
    a = @findHelper([])
    b = @findHelper(['a', 'b'])
    await Ember.RSVP.hash({ a, b })
    Ember.RSVP.resolve()

  wait: ->
    await Ember.RSVP.hash(@loading)
    console.log 'done awaiting'

The issue in our case is that done awaiting is printed before resolved. In this test case it doesn't but in our code it does. :) That is, when the wait method is called, @loading contains the two promises that were set in findHelper but awaiting them doesn't actually do that.

If we change the 2 awaits to .thens then it works fine. Can you see anything wrong that we should not be doing?

Another question - awaiting a promise returns a native promise rather than an RSVP one. This is in the context of an Ember app. Can this be changed somehow?

[sukima]

No, in an ember app it requires an RSVP promise because RSVP is monkey patched to handle an ember run loop. Native promise do not have this. There is history concerning this at emberjs/rfcs#175 but unfortunately it is unlikely to have a solution.

Good news is that there is a very usable and helpful workaround with the ember-co addon which works great for this very use case.

[stefanpenner]

Another question - awaiting a promise returns a native promise rather than an RSVP one. This is in the context of an Ember app. Can this be changed somehow?

I don't believe this can be changed currently.

---

@boris-petrov can you provide a runnable example? I will gladly debug if one is provide

[boris-petrov]

@stefanpenner - about the first thing - isn't doing a:

import { Promise } from 'rsvp'

export default
  name: 'promise'
  initialize: ->
    window.Promise = Promise

Doing exactly that?

About the second thing - I really tried hard reproducing the problem but could not find a short version (or one that I can publish). :( I currently don't have the time to try again. If you prefer, you could close the issue and I will create a new one if/when I manage with a reproduction. Or hopefully the problem just goes away by itself.

[stefanpenner]

import { Promise } from 'rsvp'

export default
name: 'promise'
initialize: ->
window.Promise = Promise
Doing exactly that?

I don't believe so, not with Native AsyncAwait at-least (potentially though with polyfills)

[stefanpenner]

If you prefer, you could close the issue and I will create a new one if/when I manage with a reproduction. Or hopefully the problem just goes away by itself.

Unfortunately I think I will need to. I tried some experiments and was also unable to find an issue...
I will gladly reopen if I can get further info/reproduction, but currently I am not sure what I can do. :(