Best Practices for Managing Asynchronous Updates in Angular Controllers

Let me explain my current setup -- I have a controller that utilizes a service to perform some tasks and then fetches data asynchronously. Right now, the data is returned after a timeout, but ideally it would involve more complex operations:

This is how my code looks like:

<div ng-controller="RootController as root">

  <h1>Angular Project</h1>
  <div ng-show="{{root.greeting}}">
    <p>{{root.greeting}}</p>
  </div>

</div>

The Controller part:

(function(){

  'use strict';

  function RootController(greetingService) {

    var vm = this;
    vm.greeting = '';

    // Initialization logic
    activate();

    function activate() {
        greetingService.greeting().then(
          function( response ) {
              vm.greeting = response;
          },
          function( error ) {
              vm.greeting = error;
          }
        );
    }
  }
  RootController.$inject = ['greeting'];
  angular.module('app.core').controller('RootController', RootController);

})();

The Service section:

(function() {
  'use strict';

  // Greeting Service
  function greeting( $timeout ) {

    // public API
    var service = {
        greeting:   greeting
    };
    return service;

    // internal functions
    function greeting() {
        return $timeout( function() {
            return 'Hello world!'; 
        }, 1000 );
    }

  }

  temp.$inject = ['$timeout'];
  angular.module('app.core').factory( 'greeting', greeting );

})();

My Concerns:

  1. Why isn't my view updating when the timeout completes and the vm.greeting assignment takes place in my controller? I've heard about the concept of "inside Angular vs outside Angular", but I believe I'm still within the Angular environment.

  2. I know about $scope.$apply(), however, I faced the "digest is already in progress" error, which makes me question if there's a better approach.

  3. Should I reconsider how I organize my components? I've tried using broadcasting events over $rootScope and setting up event handlers in the Controller, but it leads to the same issue of the view not reflecting the asynchronous model changes.

Answer №2

It appears that the way you've organized your code is quite unique compared to my usual approach. I recommend checking out this link for a detailed style guide:

Regarding your current issue, Angular utilizes $scope to connect a value in the controller to the view. Therefore, ensure that your controller has $scope injected so you can utilize $scope.greeting instead of vm.greeting.

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