Conditional injection of a service in AngularJS

Question

I have defined a service like this :

angular.module('myApp').service('myService', [
'$rootScope',
...
...

I want my service to be instantiated only for new user (i.e. when user.createdAt > today).

So is there a way to conditionally inject my service or at least destroy my service without any side effect if the user is an old one.

Answer 1

You can use the $injector service to get inject-ibles dynamically if you need to:

app.controller('DemoCtrl', function($injector) {
  this.clicky = function() {
    myFact = $injector.get('myFactory');
    myFact();
  };
});

app.factory('myFactory', function() {
  return function() {
    alert('foobar!');
  };
});

Here's a full running demo: http://jsbin.com/bemakemaja/1/edit

And the $injector docs: https://docs.angularjs.org/api/auto/service/$injector

As a general guideline though I'd recommend not designing your services such that simply injecting them has side effects.

Answer 2

use factory instead of service, so that you can have some checking logic in your service

angular.module('myApp').factory('myService', function () {

    if (newUser) {
        return { // your service implementation here
        }
    }
    return undefined;
};

Answer 3

So is there a way to conditionally inject my service or at least destroy my service without any side effect if the user is an old one.

Best to capture this logic inside the service:

class Service{
    static $inject = ['$rootScope'];
    constructor($rootScope){
        if (user.createdAt > today){ /*something*/ }
        else {/*other thing*/}
    }
}

NOTE: services are singletons so conditional injection doesn't see like a desirable solution. Also to learn about $inject : https://www.youtube.com/watch?v=Yis8m3BdnEM