Angular promise difference localhost vs deployed

Question

I'm doing a call to a REST service which returns true or false.

function topLevelClosed($stateParams) {
  var id = $stateParams.id;
  return id ? Traject.topLevelClosed({id: id}).$promise : false;
}

var topLevelClosed = {
  method: 'GET',
  url: trajectURL + ':id/topLevelClosed'
};

topLevelClosed is a $resource method. This works perfectly localhost. The topLevelClosed var is 'false', which is equal to the value returned by the REST call. However when deployed (to Google App Engine), I get the result "wrapped in a promise" as seen in the image below. However when I call the REST-service through the browserwindow, it returns false as it should.

promise result when deployed

promise result on localhost

Why won't this work when deployed?

konqi · Accepted Answer · 2016-05-09 08:36:22Z

2

The behavior you describe is what i would expect for this code. When your function returns a promise your call would look like this

topLevelClosed($stateParams).then(function(value){
  /* do something with value */
});

if instead topLevelClosed returns a boolean then you can access the value directly without the then(...).

To get consistent behavior i would always return a promise, like this:

function topLevelClosed($stateParams) {
  var deferred = $q.defer();
  if(id){
    Traject.topLevelClosed({id: id}).$promise.then(function(value){
      deferred.resolve(value);
    });
  } else {
    deferred.resolve(false);
  }
  return $q.promise;
}

Well this isn't as pretty as i hoped it would be but you can improve it. I do however recommend that you always use a consistent return type. When you mix booleans and promises you have to analyze the return value's type before continuing.

edited May 9, 2016 at 8:36

answered May 9, 2016 at 8:01

konqi

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4 Comments

Robin-Hoodie Over a year ago

He's injecting $stateParams, so this is most likely a resolve method. In a resolve method it doesn't matter if you're returning a promise or not, if it's a promise the router will resolve it for you so you'll always end up with either the resolved promise or in this case the primitive false

konqi Over a year ago

@NexusDuck You may want to elaborate on how a $resource method's result ends up in the ui-router to be automatically resolved. I don't see injection here. The only thing i see is a function with a parameter and i don't know how that function is called.

Robin-Hoodie Over a year ago

Well, $stateParams is a ui-router service, typically used in resolve functions

konqi Over a year ago

From the code in the question i would guess that the function is called and $stateParams is forwarded as an argument, and because we're all lazy when it comes to naming variables the argument variable has the same name in the function. I don't want to jump to conclusions. We probably need more information from the op. I tend to delete my answers that don't match the question, so there should be no harm done.

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