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I have been experimenting with returning synchronous results from an aura:method called by a parent component. I have observed two use cases in which results are never returned:

  1. When the aura:method is called from a function that is invoked from an event handler
  2. When the aura:method is called from $A.getCallback()

Does this mean that aura:method can only return "synchronous" results in the context of the framework lifecycle - i.e. the results will not be available to a calling function invoked in an asynchronous context?

This makes sense on a certain level, but I'm struggling with the "why" behind this.

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  • I am at a loss as to how to return a synchronous result, as every use case I test returns 'undefined' for the var that references the method providing the return. – Mike Topalovich Feb 14 '18 at 13:16
  • Can you give a code example? From what I understand of your question, I've used scenario 1 successfully, so there may be some subtlety that's not obvious without the code. – Aidan Feb 14 '18 at 14:12
  • I will work on abstracting a code sample. What I'm building right now would be too complex to follow without a ton of annotation. I've narrowed my hypotheses down do this either being a limitation in the data types that can be returned (seems OK with String when using a simple controller action, but Object or Object[] always returns undefined), or an issue with the return for the method occurring in a function call in the Helper down the stack. Unfortunately I had to give up and go back to using an event-driven model. – Mike Topalovich Feb 14 '18 at 15:56
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Both of this use cases , calls for asynchronous action or a callback .The docs hint at this a little

Asynchronous code can continue to execute after it returns. You can’t use the return statement to return the result of an asynchronous call because the aura:method returns before the asynchronous code completes. For asynchronous code, use a callback instead of a return statement.

Hence what i think is you just need to use callback pattern documented here

Essentially pass a function as attribute and set the callback .

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