AngularJS: need to fire event every time an ajax call is started

Question

I am trying to fire an event on $rootScope every time an ajax call is started.

var App = angular.module('MyApp');

App.config(function ($httpProvider) {
    //add a transformRequest to preprocess request
    $httpProvider.defaults.transformRequest.push(function () {
        //resolving $rootScope manually since it's not possible to resolve instances in config blocks
        var $rootScope = angular.injector(['ng']).get('$rootScope');
        $rootScope.$broadcast('httpCallStarted');

       var $log = angular.injector(['ng']).get('$log');
       $log.log('httpCallStarted');
    });
});

The event 'httpCallStarted' it's not being fired. I suspect that it's not correct to use $rootScope or any other instance service in config blocks. If so, how can I get an event everytime an http call is starting, without having to pass a config object in every time I am making a call?

Thanks in advance

Answer 1

You could always wrap $http in a service. Since services are only set up one time, you could just have the service factory set up the events for you. It feels a little hackish to me, honestly, but it's a good work around, since Angular doesn't have a global way to do this yet, unless something was added in 1.0.3 that I'm not aware of.

Here's a plunker of it working

And here's the code:

app.factory('httpPreConfig', ['$http', '$rootScope', function($http, $rootScope) {
    $http.defaults.transformRequest.push(function (data) {
        $rootScope.$broadcast('httpCallStarted');
        return data;
    });
    $http.defaults.transformResponse.push(function(data){ 
        $rootScope.$broadcast('httpCallStopped');
        return data;
    })
    return $http;
}]);

app.controller('MainCtrl', function($scope, httpPreConfig) {
  $scope.status = [];

  $scope.$on('httpCallStarted', function(e) {
    $scope.status.push('started');
  });
  $scope.$on('httpCallStopped', function(e) {
    $scope.status.push('stopped');
  });

  $scope.sendGet = function (){ 
    httpPreConfig.get('test.json');    
  };
});