How to make Parse Database Relations Query?

Question

I'm trying to make a query to get some data from my database but I can't seem to figure out how.

My database looks like this:

_User

Group

| objectId | group_name | .. |

Activity

My goal is to show all the activities the current user (logged in) is linked to. So a user can be part of a group (relation), and a group can have multiple activities. The activities have a pointer to Group.objectId. How can I show the activities of the group that the current user is a member of?

Currently this is my code:

    ParseObject current = ParseUser.getCurrentUser();
    ParseRelation relation = current.getRelation("groups");
    ParseQuery query = relation.getQuery();

    ParseObject test = new ParseObject("group");
    String ObjectId = test.getObjectId();

    ParseQuery<ParseObject> query2 = new ParseQuery<ParseObject>("Activity");
    query2.whereEqualTo("group_name", ObjectId);

..

@Override
    protected void onPostExecute(Void result) {
    // Locate the listview in listview_main.xml
    listview = (ListView) findViewById(R.id.listview);
   // Pass the results into an ArrayAdapter
    adapter = new ArrayAdapter<String>(MainActivity.this, R.layout.activity_main_listview_item);
    // Retrieve object "name" from Parse.com database
    for (ParseObject query : ob) {
        adapter.add((String) query.get("activity_name"));
    }

The answer is in the Parse Guide:

Parse Guide

Robert Rowntree Robert Rowntree · Accepted Answer · 2015-01-22T00:33:27

not sure that you could do the following with 2 queries...

Get a set of groups for the currentUser as a queryResult $myGroupQ the set of groups that a user belongs to

Query 2 using "query.include("groups")

Query 2 is query.Activity with Condition:

   query.whereContainedIn("groups", $myGroup);

as long as var myGroup is ofType=Array, this should work.

so using the $myGroup from qry1 as the constraint setOfValues in query #2's "containedIn"

from the android docs section on query constraints

How to make Parse Database Relations Query?

2 Answers