Managing Network Callbacks

[nesquena]

Guide on managing callback complexity

Could you please send me some code example for structuring a chain of callbacks?

For example using includes to join data or ParseRelation to load associations.

Also, move the callbacks into an object with each request in a method and then use an interface to send out the requests (pseudo-code):

class ObjectFetcher {
    public interface FetcherCallbacks {
         void onFirstDataLoaded(Model impartialData);
         void onAllDataLoaded(Model data);
    }

    FetcherCallbacks callback;
    int requestsLoadedFlag = 0;

    public ObjectFetcher(FetcherCallbacks callback) {
     this.callback = callback;
    }

    public void loadAll() {
         sendFirstRequest();
         sendSecondRequest();
         sendThirdRequest(); 
    }

    private void sendFirstRequest() {
          object.findAllInBackground(new Parse {
               void onDone(Error error) {
                    requestsLoadedFlag +=1;
                     // STORE DATA IN MEMBER VARIABLE HERE
                    callback.onFirstDataLoaded(data);
                    sendFinalDataWhenReady();
               }
          });
    }

    private void sendSecondRequest() {
          object.findAllInBackground(new Parse {
               void onDone(Error error) {
                    requestsLoadedFlag +=1;
                    // STORE DATA IN MEMBER VARIABLE HERE
                    sendFinalDataWhenReady();
               }
          });
    }

   private void sendThirdRequest {
       object.findAllInBackground(new Parse {
               void onDone(Error error) {
                    requestsLoadedFlag +=1;
                    // STORE DATA IN MEMBER VARIABLE HERE
                    sendFinalDataWhenReady();
               }
        }
   } 

   private void sendFinalDataWhenReady() {
      if (requestsLoadedFlag == 3) {
          callback.onAllDataLoaded(data1, data2, data3);
      } 
   }
}

and then use with something like:

ObjectFetcher fetcher = new ObjectFetcher(new FetcherCallbacks() {
     void onFirstDataLoaded {
          // … callback fired here
     }

    void onAllDataLoaded {
          // … callback fired here
     }
})

Note that this is psuedocode but hope it gives you an idea of how to manage things using objects and interface callbacks.