Angular js - services and circular injection error

Question

Why does i can't inject services like this?

service('actionService',function (sessionService) {
 this.doAction = function () {
  return 5;
 }
});
service('sessionService',function (userService) {
 this.get = function {
    if(userService.check()){
    //do other stuffs 
    }
  }

});
service('userService',function (actionService) {
  this.check = function () {
  actionService.doAction();
  if(x = 9){ 
    return true;
  }else{ 
   return false; 
  } 
  }
});

I get "Circular injection error" in console

how to handle this now ?

here a better code : http://pastebin.com/wS32UNCq

JSager · Accepted Answer · 2014-04-23 18:34:45Z

2

Before you can have an instance of actionService, you need to inject an instance of sessionService.

Before you can have an instance of sessionService, you need to inject an instance of userService.

Before you can have an instance of userService, you need to inject an instance of actionService.

It's a chicken or the egg problem... because Angular uses constructor injection, it can't instantiate a service until all of its dependencies are satisfied. But the dependencies go around in a circle, none of them can ever be instantiated.

To solve this problem, you will need to extract a shared dependency out to an additional service which can be instantiated without dependencies.

answered Apr 23, 2014 at 18:34

JSager

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6 Comments

Filippo oretti Over a year ago

hey thanks mate, but can you please go ahead explaining the last part about **shared dependency ** if you have some example just to get what you are explaining me, thanks!

JSager Over a year ago

Sure, I don't mind. Can you explain to me first why the action service depends on the session service? It's a bit tricky to try to unravel without the real code in front of me.

Filippo oretti Over a year ago

sure later i'll try pasting the real code, anyway sessionService gets user profile by userService and sets the user session, then actionService checks (by sessionService) if user session exists and redirects not logged users....(in two words) ;P

JSager Over a year ago

OK, for the moment I'd like to take this in a very different direction. Are you using the AngularJS routing stuff to load your partials?

Filippo oretti Over a year ago

sure $routeProvider you mean? i'm using it

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