Injecting $state into a service does not seem to work (resolves, but no functionality)

[scribblet]

Hi,

I have written a factory service that has $state injected.

  angular.module('authService', ['taprApi', 'ui.router']).factory('authService', function($document, $state, taprApi) {
      var authService = {
      ....
      };
      return authService;
    }

The problem is whenever I call $state.go() inside a function attached to a property on authService, nothing happens. What is the logical solution here?

I realise the problem may be with my approach (perhaps services should never be able to transition to another state, and this is by design) and not with the library. I am unsure of where to ask for help/clarification.

[laurelnaiad]

If you put a plunker together, I bet someone will help here.

[laurelnaiad]

Oh... nothing wrong with calling one service from the other btw.

[scribblet]

I will set up a plunkr today (just got into work) and see if I can't replicate the problem!

Cheers

[scribblet]

Ok, I managed to solve the issue but the resolution seems in no way related to the original problem. I decided to move the state transition back into the controller and use a deferred within my service method. The deferred would not resolve back to the controller level and I could not get the $state.go('dashboard') to work until I wrapped my deferred.resolve from the authService in a $timeout.

Any ideas why it works like this? So to clarify, the whole thing falls apart if I don't wrap my resolve/reject in the authService.login method with a $timeout call.

[nateabele]

No idea. Maybe if you put a working example in a plunkr, we could help you figure it out.

[scribblet]

Ok I will do that now @nateabele.

Thank you!

[scribblet]

http://plnkr.co/edit/6uKnVvEI3bJvfmaUoWN0

This demonstrates the confusing behaviour I'm talking about. If I was to wrap all the deferred.resolve in $timeout everything works as expected.

[laurelnaiad]

Huh? That plunker doesn't even use ui-router.... I think maybe if you plunk something that demonstrates how you think you should use ui-router, but that isn't working as you'd expect, and tell us how you would expect it to work...then...

[scribblet]

As I explained above Stu the resolution is totally unrelated to the original problem. I thought $state.go was failing, but it wasn't, my success function on deferred.resolve was not being called.

I guess I am still querying this because I know you guys obviously have much more experience in AngularJS and can probably point me in the right direction here. If you want me to close the issue and put it on stack overflow to get an explanation I don't mind doing that either.

Here is a plunkr of the "fix" I implemented in my own code that now makes the whole process work.

http://plnkr.co/edit/xp8NeZKWDep6cPys5gJu

Edit: my hunch is it is related to timeout forcing a digest cycle to run, allowing AngularJS to update its internal state and respond accordingly. Is this correct?

[laurelnaiad]

I think you're doing what you can, given that your services are stubs. If you call resolve before you return the promise then the recipient of the promise never sees the resolve take place, AFAIK.

[scribblet]

Sorry to prolong this any further, but I don't think that is the only issue because changing the "fix" to use setTimeout instead of $timeout results in the original problem again.

Furthermore, I've updated the plunkr to resolve the deferred object before returning the promise. This works just fine.

My guess is $timeout calls a digest cycle which seems to be affecting whether promises resolve or not when there's a nested relationship of promises on promises

This plunkr demonstrates there's no issue resolving before returning, I have used a number of Promises/A+ implementations (when.js, Q, my own) and have never had an issue resolving a promise before returning.

http://plnkr.co/edit/xp8NeZKWDep6cPys5gJu?p=preview

Thanks for your help, I really appreciate it. I might take this over to Stack Overflow and see if I can get an explanation to further my understanding of how AngularJS works internally.

[laurelnaiad]

I see your point.

[scribblet]

http://stackoverflow.com/questions/18755383/angularjs-behaving-strangely-when-theres-a-nested-relationship-of-promises-in-s

An answer was provided. Thanks again for your help here, made it easy to ask the right question!