使用Parse.com和Android，如何获得一对玩家共享的游戏列表？

Question

I am making a two-player for Android using Parse.com. I'm determining which two players are in the game by introducing a Game table on Parse.com, with an Array of the userId s of the players of the game.

I need to query Parse.com for a list of all the games shared by two given players. I thought something like this would do the trick.

    String[] userIds = new String[] {player1, player2};
    ParseQuery<ParseObject> query = new ParseQuery<ParseObject>("Game");
    query.whereEqualTo("players", userIds);

The problem is, I don't know the order of the Array of players. So about half of the time, the order will be wrong I won't get the correct result from this query. I'll get that no game exists between the two players.

So my idea to solve this was to also query for a reversed array, then OR the two queries together.

    String[] reversedUserIds = new String[] {player2, player1};
    ParseQuery<ParseObject> query2 = new ParseQuery<ParseObject>("Game");
    query2.whereEqualTo("players", reverseUserIds);
    List<ParseQuery<ParseObject>> queryList = new ArrayList<ParseQuery<ParseObject>>();
    queryList.add(query);
    queryList.add(query2);
    ParseQuery<ParseObject> mainQuery = ParseQuery.or(queryList);

However, when I run mainQuery.find() , I get an error that looks like this:

    java.lang.IllegalArgumentException: invalid type for ParseObject: class [Ljava.lang.String;

Instead of simply returning a list of all the games that both players are playing with each other.

Answer 1

You could try to force the IDs pair to be always ordered, for example doing player1.compareTo(player2) . Then you only need to query with the right order.