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I have a small dialog which should validate before close, get values from inputs and then call the callback given by dialog caller. I've realized processing inputs as function taking callback arguments, so every method in chain is asynchrone.

What I want, is to call isValid, on success callback call getValues, on success callback call okCallback. Here is my code:

var self = this
this.isValid().then(lang.hitch(this, this.getValues), function(){
  console.log('Object invalid')
  return false
}).then(function(item) {
   self.okCallback(item)
})

The problem is, that the final then() with calling okCallback is called even if isValid() finished with error, adn getValues() were not called.

Is it normal behaviour? How to make deferred chaing, so that final success callback will be called only, if everything before succeeded?

Danubian Sailor
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1 Answers1

2

Yes, that is normal behavior. You did already handle the error in 

function(){
  console.log('Object invalid')
  return false
})

from where you did return a non-error value (false). To continue with an error, throw another one, throw the same one, or don't use the second argument to then but a separate addErrback. Or put the error handler after the .then(lang.hitch(this, this.okCallback)) so it will handle errors from getValues as well without affecting the okCallback.

Bergi
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  • I should 'throw' an error, or return deferrable and call 'reject'? – Danubian Sailor Oct 18 '13 at 10:30
  • I guess you should return a rejected Promise, only [Promises/A](http://wiki.commonjs.org/wiki/Promises/A)-based implementations seem to support real `throw`ing from the handlers. – Bergi Oct 18 '13 at 10:37
  • Is there any shortcut for returning rejected promise? Creating Deferred, rejecting and returning is 3-liner... – Danubian Sailor Oct 18 '13 at 11:31
  • @ŁukaszL.: From [the docs](http://dojotoolkit.org/api/1.9/dojo/Deferred#reject) it looks as if you could use chaining, i.e. `return new Deferred().reject(reason);` – Bergi Oct 20 '13 at 15:22