Develop Reference

Returns zero for all values retrieved from the parse database

I'm using parse backend to store and retrieve the datas for my android app, the storing gets done properly but i have problem in retrieving it. I just went through the parse documentation to retrieve the result but what i get is just 0 for all the retrieved values..im suret that the class exists in the parse cloud with valid values but still i get 0 for all the queries.. this is my code to save:
Toast.makeText(getApplicationContext(),"writing to parse",Toast.LENGTH_SHORT).show();
ParseObject dataObject = new ParseObject("Score");
dataObject.put("correct",correctAnswers);
dataObject.put("wrong",wrongAnswers);
dataObject.put("percent", percentage);
dataObject.saveInBackground();
this is how i get back the saved data
ParseQuery<Score> query = ParseQuery.getQuery("Score");
try {
List<Score> scoreList = query.find();
} catch (ParseException e) {
e.printStackTrace();
}
query = ParseQuery.getQuery("Score");
final Activity ctx = this;
query.findInBackground( new FindCallback<Score>() {
#Override public void done(List<Score> scoreList, ParseException e) {
if ( e == null ) {
ParseObject dataObject = ParseObject.create("Score");
int p = dataObject.getInt("correct");
int q = dataObject.getInt("wrong");
int r = dataObject.getInt("percent");
Toast.makeText(ExamRecordActivity.this,String.valueOf(p),Toast.LENGTH_SHORT).show();
Toast.makeText(ExamRecordActivity.this,String.valueOf(q),Toast.LENGTH_SHORT).show();
Toast.makeText(ExamRecordActivity.this,String.valueOf(r),Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(ctx,
"Error updating questions - please make sure you have internet connection",
Toast.LENGTH_LONG).show();
}
}
});

Inside the done method you are creating a new by calling ParseObject dataObject = ParseObject.create("Score"); and then trying to read values from it without putting any in.
I don't know what the structure of your class is but you need to be iterating through List<Score> scoreList in order to get the queried data.

How to get only new data inserted from Parse

I'm making a small application. trying to retrieve posts inserted, and then I want to retrieve only new inserted posts, and not retrieving all the posts again.
So do you have any idea on how to I can retrieve last items ( Since the list object retrieved)
Here my Query code :
public void getFeed(int limit, int skip){
ParseQuery<ParseObject> query = ParseQuery.getQuery("Feed");
query.setSkip(skip);
query.setLimit(limit);
query.setCachePolicy(ParseQuery.CachePolicy.CACHE_ELSE_NETWORK);
query.findInBackground(new FindCallback<ParseObject>() {
public void done(List<ParseObject> feedList, ParseException e) {
if (e == null) {
for (int i = 0; i < feedList.size(); i++) {
Post p = new Post(feedList.get(i).get("Text").toString());
mAdapter.addItem(p);
}
Log.d("result", "Here is it:" + feedList.size());
mRecyclerView.setAdapter(mAdapter);
} else {
Log.d("Feed", "Error: " + e.getMessage());
}
}
});
}

keep the last time you checked and then use that time to pull anything greater than the last time checked from the createdAt column or updatedAt column (if its possible for someone to update something you are pulling) of the object. then after your query is finished update that time to the current time.

you can store the viewed posts count and next time when retrieving the list set the count as parameter for skip:
query.setSkip(count);

Parse get multiple objects using their objectIds

I have a ArrayList<String> -named listObjectId below- of objectIds. I'm trying to get all the objects that have an objectId contained in the ArrayList.
The solution I have right now, I think, is very bad from a performance point of view:
for (int i = 0; i < listObjectId.size(); i++) {
ItemModel mItemModelRetrieved = null;
ParseQuery<ItemModel > query = ParseQuery.getQuery(ItemModel .class);
try {
mItemModelRetrieved = query.get(listObjectId.get(i));
subscriber.onNext(mItemModelRetrieved ); //-- I'm using RxJava
} catch (ParseException e) {
Log.e(TAG, "Error Local " + e.getMessage());
}
}

You're using the wrong method. You have the object ids, so create a ParseObject with them using ParseObject.createWithoutData and then fetch the object. Try the following:
List<ParseObject> parseObjects = new ArrayList<>();
for (String objectId : listObjectId) {
parseObjects.add(ParseObject.createWithoutData(ItemModel.class, objectId));
}
ParseObject.fetchAll(parseObjects);
// parseObjects will now contain all data retrieved from Parse.

The error you're getting tells you that the data type of the column you query must be of type Array, not the value you pass into the method.

Getting data from Parse query

I am having some trouble getting some data from my Parse table/object with a query. I am trying to simply make a query which looks for the current Parse User's objectID in the "sender" column. When that result is returned, I want to extract the receiver's objectID from the "receiver" column associated with the user that I searched for. I keep getting 0 results, even though I know the data is there. Here is my code:
private List<String> potentialRelationQuery() {
mPotentialRelations = new ArrayList<>();
String currentUserId = mCurrentUser.getObjectId();
ParseQuery<ParseObject> query3 = ParseQuery.getQuery("PotentialRelation");
query3.whereEqualTo("sender", currentUserId);
query3.findInBackground(new FindCallback<ParseObject>() {
#Override
public void done(List<ParseObject> parseObjects, ParseException e) {
if (e == null) {
if (parseObjects.size() > 0) {
for (int i = 0; i < parseObjects.size(); i++) {
ParseUser receiver = (ParseUser) parseObjects.get(i).get("receiver");
String receiverId = receiver.getObjectId();
mPotentialRelations.add(receiverId);
}
}
} else {
Log.d("MyApp", "No matching objects returned from request");
}
}
});
return mPotentialRelations;
}

Since findInBackground is an asynchronous call to Parse isn't it possible that mPotentialRelations returns empty because the findInBackground query hasn't yet completed before the potentialRelationQuery method returns? I know I've had issues with this. Since you can't return data from an inner class (i.e. in the done method of FindCallback), writing this kind of query method has never really worked consistently for me.

Updating value in column of array type in Parse Table

I am new to parse data from parse.com.I am trying to update a column.The column in parse table is of array type.I am trying to add a value in array.For Example :
it is showing in data browser like this:
["Ado", "Wassja", "Cristi_3"]
And I want to add "ABC" value in this array programmatically like this:
["Ado", "Wassja", "Cristi_3","ABC"]
I have searched for this and got to know that first I need to fetch all the data of that particular row which I have to update ,then put the data in array I have fetch successfully the data for that particular row like this:
ParseQuery<ParseObject> query = ParseQuery.getQuery("UserMaster");
query.whereEqualTo("userName",str_uname2);
query.findInBackground(new FindCallback<ParseObject>() {
#Override
public void done(List<ParseObject> userList, ParseException e) {
dlg.dismiss();
if (e == null) {
if (userList.size()>0) {
for (int i = 0; i < userList.size(); i++) {
ParseObject p = userList.get(i);
str_dbpassword = p.getString("password");
String email = p.getString("email");
List<ParseObject> mfollowers = p.getList("followers");
List<ParseObject> mfollowing = p.getList("following");
ParseFile pp = (ParseFile)p.get("photo");
str_dbuname = p.getString("userName");
}
Log.d("password", "Retrieved " +str_dbpassword +"<uname>"+str_dbuname);
}
}
else {
Alert.alertOneBtn(LoginActivity.this,"Something went wrong!");
}
}
});
Now I have to update data in
List<ParseObject> mfollowers = p.getList("followers");
And
List<ParseObject> mfollowing = p.getList("following");
I don't know how to do this.Please help me.Your small clue will be very helpful.

Per the docs: http://parse.com/docs/android/api/com/parse/ParseObject.html
You can use add, addUnique, addAll, or addAllUnique to add elements to an array on a Parse Object:
someParseObject.add("arrayColumn", "ABC");
someParseObject.saveEventually();

To expand on Fosco's answer:
ParseObject parseObject = new ParseObject("YOURCLASS");
String[] stringArray = ["Ado", "Wassja", "Cristi_3"];
List<String> stringArrayList = new ArrayList(Arrays.asList(stringArray));
if (stringArray != null)parseObject.addAll("YOURCOLUMN", stringArrayList);
Make sure that the security settings for YOURCLASS enable you to create columns automatically or that you have the correct types set for your columns.
I hope that completes Fosco's answer.