angularjs - Is there a shortcut to proxy-resolve/reject a promise to an Angular $q deferred?

Question

Given an unresolved deferred (dfd), and a then-able promise (promise), which may or may not be deferred, is there a way to 'proxy' the promise into the deferred?

The semantics should be as so:

promise.then(dfd.resolve, dfd.reject);

The $q documentation only mentions handling of rejected promises (and furthermore, only promises rejected in a certain way):

defered.resolve(value) – resolves the derived promise with the value. If the value is a rejection constructed via $q.reject, the promise will be rejected instead.

This makes it unclear if dfd.resolve(promise) is valid/supported. Also, I cannot use $q.when (which does take a then-able) because the promise of the defered has already been returned.

The Angular version is 1.2.x.

Answer 1

Yes.

Any time you resolve a promise to another promise (whether by resolve() or by returning from a callback), it will implicitly wait for that other promise.

In fact, it is impossible to make a promise actually resolve to another promise instance (without waiting).