Managing Network Callbacks

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):

``` java
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:

``` java
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.