Angularjs sharing data between controllers

Question

I have a service that fetches some client data from my server:

app.factory('clientDataService', function ($http) {
    var clientDataObject = {};
    var cdsService = {
        fetch: function (cid) {
            //$http returns a promise, which has a then function, which also returns a promise
            var promise = $http.get('/clients/stats/' + cid + '/').then(function (response) {
                // The then function here is an opportunity to modify the response
                console.log(response);
                // The return value gets picked up by the then in the controller.
                clientDataObject = {'data': response.data, 'currentClientID': cid};
                return clientDataObject;
            });
            // Return the promise to the controller
            return promise;
        }
    };
    return cdsService;
});

Then in one controller I do:

//get stats
clientDataService.fetch($scope.id).then(function (response) {
    $scope.client_data = {
        'statistics': response.data
    }
});

Which all works very well. However, I'm trying to do a watch from another controller on that service to update it's scope when the data changes, rather then having to re-kick off the http request:

$scope.$watch('clientDataService.clientDataObject', function (cid) {
    alert(cid);
});

I'm just alerting for now, but it never ever triggers. When the page initially loads, it alerts "undefined". I have no errors in the console and all the $injects are fine, but it never seems to recognize that data has changed in the service. Am I doing something wrong in the watch?

Many thanks Ben

Answer 1

clientDataService.clientDataObject is not part of your controller's scope, so you can't watch for changes on that object. You need to inject the $rootScope into your service then broadcast the changes to the controllers scopes.

app.factory('clientDataService', function ($rootScope, $http) {
    var clientDataObject = {};
    var cdsService = {
        fetch: function (cid) {
            var promise = $http.get('/clients/stats/' + cid + '/').then(function (response) {
                // The then function here is an opportunity to modify the response
                console.log(response);
                // The return value gets picked up by the then in the controller.
                clientDataObject = {'data': response.data, 'currentClientID': cid};
                $rootScope.$broadcast('UPDATE_CLIENT_DATA', clientDataObject);
                return clientDataObject;
            });
            // Return the promise to the controller
            return promise;
        }
    };
    return cdsService;
});

Then in the controller you can listen for the change using:

$scope.$on('UPDATE_CLIENT_DATA', function ( event, clientDataObject ) { });

Answer 2

Another approach can be:

1. define new service

   app.factory('DataSharingObject', function(){
      return {};
   }
   

2. include this new service in controller where we want to store the data

   app.factory('clientDataService', function ($http, DataSharingObject) {
       DataSharingObject.sharedata = ..assign it here
   }
   

3. include this new service in controller where we want to access the data

   app.factory('clientReceivingService', function ($http, DataSharingObject) {
      ..use it here... = DataSharingObject.sharedata
   }