解析listview中的ParseQueryAdapter和多对多关系[Parse.com]

Question

I am developing an android application and I really liked parse and planning to use it again in future projects. So this app is my senior project...

1st. I tried a many-to-many "_User"relation but couldn't figure out the queries or couldn't add another user to the existing user relation successfully.

2nd. I created a "contact" ParseObject class pointing for each user pointing at it's creator, and I could successfully add other contacts into a contact, it's contact-to-contact relation and I called it "has"

3rd. And now I can see the relation in my data browser,and everything including (create, update, delete, get)is going great... BUT MY PROBLEM IS #4 !

4rth. I have a class that extends ListFragment and I want to query the contacts in my "contact" relation for the ParseQueryAdapter... I tried all the methods and I either get a null pointer exception or my app crashes...

I can get all the contacts to show though using this line of code:

ParseQueryAdapter adapter = new ParseQueryAdapter(getActivity(), MyContactClass.class);

But tried all the queries in relational tutorials and it didn't work out... I understand Parse logic but can't figure out the code implementation...

A [contact] has ---> a [List}...... I want to get that list, any Java sample code to do that?

PLEASE AND THANK YOU :) I never ask a question unless I'm desperate...

Answer 1

I was able to solve this by NOT using the getInBackground(with Callback) method... I modified the code to the following:

ParseQueryAdapter<ParseObject> adapter = new ParseQueryAdapter<ParseObject>(getActivity(), new ParseQueryAdapter.QueryFactory<ParseObject>() {public ParseQuery<ParseObject> create() {
                                  // Here we can configure a ParseQuery to our heart's desire.

                                    final ParseQuery<ParseObject> cUser = ParseQuery.getQuery("contact");


                                    ParseQuery<ParseObject> query = new ParseQuery<ParseObject>("contact");
                                    try 
                                    {
                                        query=cUser.get("MyObjectIdGoesHere").getRelation("has").getQuery();
                                    } catch (ParseException e) 
                                    {
                                        e.printStackTrace();
                                    }
                                  return query;

                                }
                              });


        adapter.setTextKey("screenName");
        setListAdapter(adapter);

It was really frustrating and I hope that someone could benefit from the solution that fitted my code...

Answer 2

Sorry to hear that. By chance I had Parse Android Anywall Project opened with my project. In this example project, the following code can help achieve your goal.

I tried to post codes here, can't past the formatting requirement of stackoverflow.