Objects returned from promise are undefined

Question

I am trying to wrap the getstream API in an angular service (factory)

Here is my code:

.factory('FeedStream', function($http, $q) {

    var client = stream.connect('xxxxxxxxxxx');

    return {
        feed : function() {
            $http.get('/api/feed/auth/')
            .success(function(auth) {

                var user_feed = client.feed('user', auth.user, auth.token);
                console.log(user_feed.get());

                user_feed.get().then(function(data) { 
                    console.log(data);
                    return data;
                })
            })
        },
    }

First I get the user_id and auth token from my server using the endpoint /api/feed/auth/. This data is returned in an angular promise.

Next, I use this data to call the getstream api to get the user_feed object. If I return this object (user_feed) it is undefined in the controller. If I print it to the console here in the service, it has the correct value. I've noticed that the print happens half a second or so after the return. Why is the assignment of this variable happening asynchronously?

Now if I call the get method on this user_feed object inside a console.log statement, a Javascript promise object is printed out. If I return user_feed.get() it returns undefined to the controller. If I call it here in the service like in my code above, and return the data object in the promise then statement, it returns undefined to the controller. However if I print the data object, it has the correct value.

Why can't I return any objects from this service? Am I missing some fundamental aspect of using promises?

None of your functions actually `return` anything, and you must not use `success` instead of `then`. — Bergi, Mar 30 '16 at 21:49

Pankaj Parkar · Accepted Answer · 2016-03-30T22:17:11.760

You haven't returned feed promise object as well as data haven't been returned from feed method correctly. So for achieving the same thing do use .then over $http to maintain promise chaining

Code

return {
    feed : function() {
        //return `$http.get` promise
        return $http.get('/api/feed/auth/')
        .then(function(response) {
            var auth = response.data;
            var user_feed = client.feed('user', auth.user, auth.token);
            console.log(user_feed.get());
            //return `$http.get` to return internal promise
            return user_feed.get().then(function(data) { 
                console.log(data);
                return data;
            })
        })
    },
}

Controller

FeedStream.feed().then(function(data){
   console.log("data returned by user feed", data)
})

Thank you. This has helped me understand promises better. – roob Mar 30 '16 at 22:21 — roob, Mar 30 '16 at 22:21

Objects returned from promise are undefined

1 Answers1