angular.injector.invoke makes my controller undefined

Question

While learning angular, read a blog which elaborate that

we can access factory/service outside of controller using angular.injector() , But when I try this, it gives my main controller is undefined error and everything stops working.

see the working plunker with commented culprit code block.Below is main code of lines using angular.injector(["app"]).invoke

var app = angular.module('AlphaModule', []);
// service added 
app.service('tea', function(){
    return {
        teaType: function(teaType) {
            console.log('Service => Morning tea must be ' + teaType);
        },
        sayHello: function(msg) {
            console.log('Service  => Hello ' + msg);
        }
    };
});

// ERROR in console when uncomment this code block
angular.injector(["app"]).invoke(function(tea){
    tea.sayHello('Yellow');
});

// main controller definition
var AlphaController = function($injector, tea) {
    var vm  = this;
    vm.timeNow = new Date().getTime();
    ....
};

app.controller('AlphaController', AlphaController );

Please highlight what am I missing/ wrong doing here?

My Guess:

I also read that $injector are singleton . What exactly this means? can we use $injector only once! or may be this is the issue as i have used $injector in .controller also

Answer 1

Your module name mentioned is wrong. module name is actualy AlphaModule not app.

angular.injector(["AlphaModule"]).invoke(function(tea){
    tea.sayHello('Yellow');
});