javascript - AngularJS constants

Question

Is it possible to inject a constant into another constant with AngularJS?

e.g.

var app = angular.module('myApp');

app.constant('foo', { message: "Hello" } );

app.constant('bar', ['foo', function(foo) { 
    return { 
        message: foo.message + ' World!' 
    } 
}]);

I need the use of an angular constant because I need to inject this into a config routine. i.e.

app.config(['bar', function(bar) {
    console.log(bar.message);
}]);

I know that you can only inject constants and providers into config routines, and my understanding is that you can do dependency injection into providers, however, it does not seem to be the best method for this sort of scenario...

Thanks in advance for your help!

Answer 1

You are correct, it's impossible to register both foo and bar as constants.

Also for using a provider as a workaround, you almost got it right except that you have to store data in a provider instance:

var app = angular.module('myApp', []);

app.constant('foo', {
    message: 'Hello'
});

app.provider('bar', ['foo', function(foo) {
  this.data = {
    message: foo.message + ' World!'
  };

  this.$get = function() {
    return this.data;
  };
}]);

and then in config block, inject a bar's provider instance (not a bar instance as it isn't available yet in the config phase):

app.config(['barProvider', function(barProvider) {
  console.log(barProvider.data.message);
}]);

Hope this helps.