CODEWITHSUNDEEP
javaandroidcallbackparse-platform
Dannyvdz
Dannyvdz

Reputation: 57

Return object data from parse object query callback

I am quite new to Java/android programming and I'm stuck at the Parse.com callback.

In have a method (method1) that requests the objectId of an object owned by the current user. It does this by calling upon another method (method2) that contains a query which pulls an object from the data browser with a callback.

I managed to write all code but I'm stuck at the callback for method 2. I want the object data to be returned to method 1 but this seems to be inpossible because of the Callback type (void).

I also do now know how to let the rest of the method wait for the callback to return before executing.. I would appreciate it if anyone could help me out.

This is my code:

public void method1(){
    String objectId = null;

    objectId = QueryStatisticObjectId("Age");

    Log.i(TAG, "objectId returned to method = " + objectId);
}



    public String QueryStatisticObjectId(final String statistic){
        ParseQuery<ParseObject> query = ParseQuery.getQuery("Statistics");
        query.whereEqualTo("user", ParseUser.getCurrentUser());
        query.whereEqualTo("statistic", statistic);
        query.getFirstInBackground(new GetCallback<ParseObject>() {
            @Override
            public void done(ParseObject object, ParseException e) {
                if (e == null){
                    //We have data!
                    String objectId = object.getObjectId();
                    return;
                }
                else
                {
                    //Something went wrong!?!
                    e.printStackTrace();
                }
            }
        });

Upvotes: 1

Views: 2270

Answers (2)

user2097310
user2097310

Reputation:

I am having the same issue, the callbacks are really annoying, seems like they fire randomly, and the return type of void makes Overriding everything neccessary. I solved your problem by using regular .find() without the callback. I then did all the grunt work using custom code.

Upvotes: 0

mbm29414
mbm29414

Reputation: 11598

So, what you're trying to do isn't available using Parse in iOS or Android. I think it will probably work the way you want on .NET (using the Await keyword).

Instead, ask yourself:

  1. Why do you want to architect your class in this way?
  2. Why is it important to return the value to the original method?
  3. Is it just because you want a method that is recyclable?
  4. Is it because you want to handle the value in a method context that makes more sense?

If so, try something like this:

public void method1() {
    QueryStatisticObjectId("Age", new GetCallback<ParseObject>() {
        @Override
        public void done(ParseObject object, ParseException e) {
            if (e == null) {
                String objectId = object.getObjectId();
                Log.i(TAG, "objectId returned to method = " + objectId);
            } else {
                Log.i(TAG, "objectId not found");
            }               
        }
    });
}

public void QueryStatisticObjectId(final String statistic, GetCallback<ParseObject> callback) {
    ParseQuery<ParseObject> query = ParseQuery.getQuery("Statistics");
    query.whereEqualTo("user", ParseUser.getCurrentUser());
    query.whereEqualTo("statistic", statistic);
    query.getFirstInBackground(callback);
}

In this way, you can write the code to handle the returned result in the context (method1()) that makes sense, while also re-using the query method as much as you like. Additionally, as opposed to @JimW's answer, this doesn't utilize synchronous web calls, which will also afford you the opportunity to keep your app's UI responsive.

Upvotes: 2

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