Using Angular's filter service within a controller

Just starting out so please be kind!!

Encountering an issue with Angular 1.3 while using a Stateful Filter within a controller.

In brief, when utilizing the $filter('custom')(data) method instead of the {{ data | custom }} method - and the custom filter gets updated (e.g., due to a service update), only the inline ( {{ }} ) filter reflects the changes on the view.

Check out the Plunkr here: http://plnkr.co/edit/nukioL3ORnl9KDPHmNoY?p=preview

(function(angular) {
  'use strict';
  angular.module('myStatefulFilterApp', [])
    .filter('decorate', ['decoration',
      function(decoration) {

        function decorateFilter(input) {
          return decoration.symbol + input + decoration.symbol;
        }
        decorateFilter.$stateful = true;

        return decorateFilter;
      }
    ])
    .controller('MyController', function($filter, $scope, decoration) {
      $scope.greeting = 'hello';
      // This will update
      $scope.decoration = decoration;
      // This won't
      $scope.code = $filter('decorate')($scope.greeting);
    })
    .value('decoration', {
      symbol: '*'
    });
})(window.angular);

I've experimented with different solutions for this issue, including event listeners, but it seems that none of those will solve the problem.

This problem initially arose from using the date filter and the locale plugin that dynamically updates the locale, resulting in the filter not updating when the locale changes.

Any suggestions on how to make the code-based filter monitor changes (possibly using a $watch task) are greatly appreciated.

Thanks in advance.

- Adam

Answer №1

When it comes to the controller, it is executed just once and not every single time the scope updates. The expression

$filter('decorate')($scope.greeting)
gets evaluated during the assignment to $scope.code, whereas {{greeting | decorate}} gets evaluated whenever the scope updates.

If your filter isn't marked as stateful, then the filter expression {{greeting | decorate}} will only get evaluated upon updating of greeting. However, all this does not impact the behavior within the controller.

To ensure that $scope.code gets updated every time there is a change in $scope.greeting, you can use $scope.$watch:

$scope.$watch('greeting', function(newValue) {
    $scope.code = $filter('decorate')(newValue);
});

Answer №2

    Have you considered using the $watch method? It could potentially solve your issue.

    Check out the updated code snippet below:

http://plnkr.co/edit/4IlBIhh2JfmPcMDW0ty6?p=preview

    Hopefully, this suggestion proves helpful to you.

    Appreciate it!

Answer №3

I came up with a solution that doesn't involve using $watch, instead utilizing a function attached to ng-change in the input field.

  $scope.update = function(){
    $scope.code =$filter('decorate')($scope.greeting);
    };

Check out my solution on Plunker here

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