Writing an angularJS poller

Question

I'm trying to write an angularJS service for long polling in my application, using $http.

Here's my code :

app.factory('Poller', function($http, $timeout){
    var poll = function(http, tick){
        http.then(function(r){
            $timeout(poll, tick);
            return r.data;
        });
    };

    return{
        poll: poll
    };
});

The basic idea would be to inject this service whenever I need polling on a $http call. I'm using it inside a controller :

app.controller('myCtrl', function($scope, $http, Poller){
    $scope.polledVar = Poller.poll($http.get('api/getVar'), 1000);
});

When using this code I get the following error :

TypeError: Cannot call method 'then' of undefined

score 6 · Accepted Answer · edited May 23 '17 at 12:09

Even if I don't understand the design (overhead design imo) here is it:

app.factory('Poller', function($http, $timeout,$q){
                var poll = function(http, tick){
                   return http.then(function(r){
                        var deferred = $q.defer();
                        $timeout(function(){
                            deferred.resolve(r);   
                        }, tick);
                        return deferred.promise;
                    });
                };

                return{
                    poll: poll
                };
            });

You could simply pass the url like Poller.poll('api/getVar', 1000);

UPDATE

just to play around :) and following https://stackoverflow.com/a/16520050/356380

var app = angular.module('myModule', []);

            app.factory('Poller', function($http,$q){
               return {
                    poll : function(api){
                        var deferred = $q.defer();
                        $http.get(api).then(function (response) {
                                deferred.resolve(response.data);
                        });
                        return deferred.promise;
                    }

                }
            });
            app.controller('myCtrl', function($scope, $http,$filter ,Poller){
                //Just to start
                $scope.myts = Poller.poll('mytest.php');
                $scope.mydate = $scope.myts.then(function(data){
                    return $filter('date')(data,'yyyy-MM-dd HH:mm:ss Z'); 
                }); 
                var Repeater = function () {
                    $scope.$apply(function () {
                        $scope.myts = Poller.poll('mytest.php');
                        $scope.mydate = $scope.myts.then(function(data){
                            return $filter('date')(data,'yyyy-MM-dd HH:mm:ss Z'); 
                        });
                    });
                };
                var timer = setInterval(Repeater, 1000);             
           });

mytest.php

echo time()*1000;

Would there be a way to pass the $scope.polledVar to the poller so that it updates it each tick ? — Lukmo, Oct 03 '13 at 09:46
do you mean like setInterval ? http://stackoverflow.com/questions/14237070/using-setinterval-in-angularjs-factory — Whisher, Oct 03 '13 at 13:49
The problem was passing the data from the service to the controller's $scope, but I used $rootScope instead. — Lukmo, Oct 03 '13 at 13:54
@Whisher: You've got the ["Forgotten Promise" anti-pattern](http://taoofcode.net/promise-anti-patterns/#theforgottenpromise) in your `poll` function. — Ben Lesh, Dec 17 '14 at 18:49
Technically, in your first poll function as well, as I believe $timeout returns a promise. — Ben Lesh, Dec 17 '14 at 18:50

score 3 · Answer 2 · answered Jul 25 '14 at 11:52

3

$interval simplifies this a good bit in 1.2+ versions of AngularJs. The video below shows how to use it.

https://www.youtube.com/watch?v=jFxPFgGaEqk

answered Jul 25 '14 at 11:52

Ryan Vice

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Writing an angularJS poller

2 Answers2