CODEWITHSUNDEEP
angularjs
aw04
aw04

Reputation: 11177

How to know when a dependency is available in angular

Given the following, $injector.get will fail as $rootScope is not available.

app.factory('$exceptionHandler', ['$injector', $injector => {
  const $rootScope = $injector.get('$rootScope')

  return (exception, cause) => {
    // code
  }
})

In researching, I keep coming across this, which works as it's resolved at runtime (when the inner function is called).

app.factory('$exceptionHandler', ['$injector', $injector => {
  return (exception, cause) => {
    const $rootScope = $injector.get('$rootScope')
    // code
  }
})

What I'd like is to somehow know when I can resolve the dependency. Something like:

app.factory('$exceptionHandler', ['$injector', $injector => {
  $injector.illLetYouKnowWhenWeCanDoStuff().then(() => {
    const $rootScope = $injector.get('$rootScope')
  })

  return (exception, cause) => {
    // code
  }
})

Is this possible?

related => $location from $exceptionHandler - dependency conflict

Upvotes: 0

Views: 69

Answers (1)

JC Ford
JC Ford

Reputation: 7066

All injectables registered through normal angular functions (factory, service, controller, etc) are available right away at bootstrap. $rootScope isn't registered normally. It's provided after the app bootstraps. Because $exceptionHandler is instantiated right away, $rootScope isn't available yet.

The best way to get around a circular dependency error is to break the circle. Let your $exceptionHandler depend on a custom service you build. Configure that new service in a .run() block into which $rootScope is injected.

app.factory('$exceptionHandler', ['myExceptionHandlingConfig', function(myExceptionHandlingConfig) {

  return function(exception, cause) {
    //do exceptional stuff
  }

}]);

app.factory('myExceptionHandlingConfig', function() {

  return {};

});

app.run(['$rootScope', 'myExceptionHandlingConfig', function($rootScope, myExceptionHandlingConfig){

  myExceptionHandlingConfig.someProperty = $rootScope.something;

}]);

Note: $rootScope will be pretty empty at bootstrap time, so you might want to set a $watch to update the service when whatever data you're looking for is available.

Upvotes: 1

Related Questions