Clear a variable before every controller call in AngularJS?

Question

Clear a variable before every controller call in AngularJS?

How can I set some model/variable before every controller call?

Currently I have the following service to help me set error messages on the page (code in LiveScript):

angular.module "project.services", 
.factory "Message", ($rootScope) ->
   {
     error :   !(msg) -> $rootScope.error = msg
     success : !(msg) -> $rootScope.success = msg
     clear :   !(msg) -> 
                   $rootScope.error = ''
                   $rootScope.success = ''
   }

and then in my index.html template:

<div ng-show="error" class="alert alert-error">{{error}}</div>
<div ng-show="success" class="alert alert-success">{{success}}</div>
<div ng-view>

But in order to use it, I have to call the clear method in every controller, otherwise the error stays on screen:

@SomeController = !($scope, $http, Message) ->
    Message.clear() # <--- have to do this

    ... rest of the controller code
    if some-error condition
       Message.error("Could not do this")
    else
       Message.success("Success!")

Is there any way to automate this clear step?

javascript
angularjs
livescript

Answer 1

If you want to clear the message after every route change, which seems to fit your use case, you can change your service to something like this:

angular.module "project.services" .factory "Message", ($rootScope) ->
  # The Message factory API.
  MessageApi = {
   error :   !(msg) -> $rootScope.error = msg
   success : !(msg) -> $rootScope.success = msg
   clear :   !(msg) -> 
               $rootScope.error = ''
               $rootScope.success = ''
  }

  # Call Message.clear whenever the route changes.
  $rootScope.$on '$routeChangeSuccess', -> MessageApi.clear!

  # Return the API.
  MessageApi