Hi All,

I have hit a bit of a snag on Android with regards to Querying a database.

I have set up an account with Parse.com which seems a very reasonable and clever solution to server hosting as a new developer.

In my set up I have 3 tables (or as Parse call them, classes) - Users, Cards, and Payer_Cards. All Users have a unique objectID, all Cards have a unique objectID and Player_Cards is a lookup between the two, containing Player ID and Card ID (not all players have all cards).

The below logic is my attempt, but for some reason I cant figure it out. I can get the Card IDs listed based on all cards against the player ID (currentUser), but when I try to expand this to look at table 3 (Cards) it all falls apart.

public void cardList(List<ParseObject> cardList){
    	StringBuilder cards = new StringBuilder();
		for(int i=0; i<cardList.size(); i++){
			cards.append("Card:");
			
			ParseObject[] cList = cardList.toArray(new ParseObject[0]);
			String cardId = cList[i].getString("CARD_ID");
			
					ParseQuery<ParseObject> query = ParseQuery.getQuery("CARDS");
			        query.whereEqualTo("objectId", cardId);
			        query.getInBackground(cardId, new GetCallback<ParseObject>() {
			            public void done(ParseObject object, com.parse.ParseException e) {
			                if (e == null) {
			                	cards.append(object.getString("CARD_NAME"));
			               } else {
			                    
			                }
			            }
			        });
	    	
    	}
		
		TextView CardsList = (TextView) findViewById(R.id.CardsList);
        CardsList.setText(cards.toString());
	}

The current error in my code is that "cards" isn't recognised within the if block.

Any assistance on this is greatly appreciated - I have exhausted all of my ides of how to get around this.

Thanks

Hi Chubu,

Thanks - that makes a lot of sense, and is kind of what I thought was happening. Can you think of a way to get around this?

I considered setting a public variable and having it set to the new string on each tick of the for loop, but seems to return null.

I imagine the main problem here is that Parse use a bit of their own terminology which no-Parse users wouldn't be familiar with? If the query didn't need that public void done() I'd probably be ok.

Thanks

Hi Guys,

Thanks for the pointer - setting the StringBuilder as an instance var works like a charm when it comes to letting me update it from various functions.

Now I just need to figure out why the CARD_NAME is blank :)

Thanks again!

Hi Again,

After some debugging I found that it is not blank, the StringBuilder just isn't populated prior to being set. Very much a simpleton question here I'm sure, but how do I synchronise my code? I've always thought it runs in order and each function is completed before it moves on.

I've changed StringBuilder to StringBuffer, and the app still compiles, but the data is still blank? I assume this is due to the synchronising you mention?

Thanks

Edit:

My ParseQuery public void section now looks like this:

public void done(ParseObject object, com.parse.ParseException e) {
			                if (e == null) {
			        			cards.append("Card: ");
			                	Log.d("Card","Contains " + object.getString("CARD_NAME"));
			                	cards.append(object.getString("CARD_NAME")+"\n");
			                	
			            		TextView CardsList = (TextView) findViewById(R.id.CardsList);
			                    CardsList.setText(cards.toString());
			               } else {
			                    
			                }
			            }

This compiles and gives me the list I expect, however when the page loads I can see the list being populated - is this something I need to drag into the very beginning and cache, or am I doing something wrong which slows it all down?

Thanks

I have looked at the documentation around the ParseQuery API but am only seeing example queries for single table queries (If Parse supported SQL I would have this nailed).

Apologies for being rather vague in my question - I felt that general practice would cover the issues I'm having here, so maybe that's not the case. My end goal is a card game (as I imagine you may have guessed), but with this snippet what I am trying to achieve is a list of cards owned by the current user. There will be situations where cards get added, I would need a separate list for a deck which will contain some of the cards in the entire list, and perhaps the ability to trade cards with other players (this part is a long way off).

I know it might appear as though I'm starting from the middle, however I am trying to ensure I can fully query the Parse database in the way that I need to before deciding it is what I want. Having read about peoples issues when taking a standalone app and making it work with users/logins, I am covering this part off first and adding the game logic to it.

Cheers