Firebase execute code IF child has been created - android

I have the following code for deleting some data form Firebase:
public void removeGameFromWaitQueue() {
final DatabaseReference data = FirebaseDatabase.getInstance().getReference().child("games").child(mCurrentGameKey);
data.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot snapshot) {
if (snapshot.exists()) {
mCurrentGame = snapshot.getValue(DatabaseModels.Game.class);
if (mCurrentGame.getState() == DatabaseModels.Game.State.OPEN.ordinal()){
data.removeValue();
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
How can i check if "data" exists, then execute all the else code? Meaning that if i create the DatabaseReference, code works. But of course if i dont create the reference, then i have null exceprion. Should i have 2 listeners for this? And if yes, how is the best way to do it?


For future reference i solved it like this:
public void removeGameFromWaitQueue() {
final DatabaseReference data = FirebaseDatabase.getInstance().getReference().child("games").child(mCurrentGameKey);
data.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot snapshot) {
if (snapshot.exists()) {
mCurrentGame = snapshot.getValue(DatabaseModels.Game.class);
if (mCurrentGame.getState() == DatabaseModels.Game.State.OPEN.ordinal()){
data.removeValue();
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
public void removeAfterCheck(){
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
rootRef.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot snapshot) {
if (snapshot.hasChild("games")) {
removeGameFromWaitQueue();
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
Probably there is a better way, but this works for me in all cases as i want.

Related

Correct way to implement search on a recyclerview with firebase?

I'm trying to implement a search function on my recyclerviewer but I'm having some trouble with it. I have created the query and the method for it,but the search does not return anything at all.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
...
...
...
mDBListener = mDatabaseRef.addValueEventListener(new ValueEventListener()
{
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
mUploads.clear();
for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
Buildings upload = postSnapshot.getValue(Buildings.class);
upload.setKey(postSnapshot.getKey());
mUploads.add(upload);
}
mAdapter.notifyDataSetChanged();
}
#Override
public void onCancelled(DatabaseError databaseError) {
Toast.makeText(MainActivity.this, databaseError.getMessage(), Toast.LENGTH_SHORT).show();
}
});
mButtonSearch.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String searchText = mSearchView.getText().toString();
firebaseUserSearch(searchText);
}
});
and i have this outside of my onCreate
private void firebaseUserSearch(String searchText) {
Query queryRef = mDatabaseRef.child("Buildings").orderByChild("name").startAt(searchText).endAt(searchText + "\uf8ff");
queryRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.hasChildren()) {
for (DataSnapshot postsSnapshot : dataSnapshot.getChildren()) {
final Buildings buildings = postsSnapshot.getValue(Buildings.class);
}
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
Is this the correct way to implement it?

firebase gets data too many times

I used recyclerview, arraylist, and firebase to get and show data, but data is added to the list too many times..
This is my code
database=FirebaseDatabase.getInstance();
mRef=database.getReference("SETS");
mRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(dataSnapshot==null) return;
for(DataSnapshot userSanpshot : dataSnapshot.getChildren())
{
if(userSanpshot.child("DETAIL").getValue()==null) break;
single.Detail=userSanpshot.child("DETAIL").getValue().toString();
/~/
list.add(single);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
adapter.setItems(list);
and this is my code when I send data to firebase
Button sharebut=(Button)findViewById(R.id.usersend);
sharebut.setOnClickListener(
new FloatingActionButton.OnClickListener() {
#Override
public void onClick(View view) {
mDatabase.child("SETS").child(userId).child("DETAIL").setValue(detailText.getText().toString());
/~/
finish();
}
}
);
}

Try Using this method
mRef.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
// do here your work
}
#Override
public void onCancelled(DatabaseError databaseError) {
// handle error here
}
});

How to execute firebase function synchronously inside for loop?

I am retrieving data from firebase database inside for loop , but problem is that firebase functions are not execute synchronously , i know firebase functions are asynchronous . is there any solution for that ?
Code :-
registrationReference.child(userId).child("generated_links").addListenerForSingleValueEvent(new ValueEventListener()
{
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
peopleModelList.clear();
for(DataSnapshot snapshot : dataSnapshot.getChildren())
{
peopleModel = new PeopleModel();
peopleHashMap =(HashMap)snapshot.getValue();
peopleModel.setChatWith((String)peopleHashMap.get("chatWith"));
peopleModel.setNickname((String)peopleHashMap.get("nickname"));
peopleModel.setChatRoom(snapshot.getKey());
Log.d("kkkk","1st");
if(peopleModel.getChatWith()!=null && !("".equals(peopleModel.getChatWith())))
{
registrationReference.child(peopleModel.getChatWith()).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
peopleModel.setRefresh_token((String)dataSnapshot.child("refresh_token").getValue());
peopleModelList.add(peopleModel);
Log.d("kkkk","2nd");
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
Log.d("kkkk","3rd");
}
iCallBackPeople.peopleAct(peopleModelList);
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Output :-
1st
3rd
2nd
But i want output like this
1st
2nd
3rd
Note :-
i searched , but never got any solution !
How to get data from Firebase Database in a loop?
Firebase addListenerForSingleValueEvent excute later in loop
I tried this but not worked for me, it is fill my list with last item !
public void listOfUsers(final ICallBackPeople iCallBackPeople) {
count=0;
//peopleModelList = new ArrayList<>();
sortedMap = new TreeMap<>();
// peopleModelList = new ArrayList<PeopleModel>(sortedMap.values());
registrationReference.child(userId).child("generated_links").addListenerForSingleValueEvent(new ValueEventListener()
{
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
// peopleModelList.clear();
for(DataSnapshot snapshot : dataSnapshot.getChildren())
{
peopleModel = new PeopleModel();
peopleHashMap =(HashMap)snapshot.getValue();
peopleModel.setChatWith((String)peopleHashMap.get("chatWith"));
peopleModel.setNickname((String)peopleHashMap.get("nickname"));
peopleModel.setChatRoom(snapshot.getKey());
//Object chatRoom = snapshot.getKey();
Log.d("kkkk","1st");
if(peopleModel.getChatWith()!=null && !("".equals(peopleModel.getChatWith())))
{
addItem(count,iCallBackPeople);
count++;
}
Log.d("kkkk","3rd");
}
Log.d("kkkk","end");
//iCallBackPeople.peopleAct(peopleModelList);
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
private void addItem(final int index, final ICallBackPeople iCallBackPeople) {
registrationReference.child(peopleModel.getChatWith()).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
peopleModel.setRefresh_token((String)dataSnapshot.child("refresh_token").getValue());
Log.d("kkkk","2nd");
sortedMap.put(index, peopleModel);
// sortedMap will sort your list by key (in this case, key is integer)
if(sortedMap.size()==2)
{
peopleModelList = new ArrayList<PeopleModel>(sortedMap.values());
iCallBackPeople.peopleAct(peopleModelList);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
I tried this but not getting all of the item only getting list with last item in snapshot
public void listOfUsers(final ICallBackPeople iCallBackPeople) {
peopleModelList = new ArrayList<>();
registrationReference.child(userId).child("generated_links").addListenerForSingleValueEvent(new ValueEventListener()
{
PeopleModel peopleModel;
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
peopleModelList.clear();
for(final DataSnapshot snapshot : dataSnapshot.getChildren())
{
peopleModel = new PeopleModel();
peopleHashMap =(HashMap)snapshot.getValue();
peopleModel.setChatWith((String)peopleHashMap.get("chatWith"));
peopleModel.setNickname((String)peopleHashMap.get("nickname"));
peopleModel.setChatRoom(snapshot.getKey());
if(peopleModel.getChatWith()!=null && !("".equals(peopleModel.getChatWith())))
{
getToken(new CallBackGetToken() {
#Override
public void token(String token) {
peopleModel.setRefresh_token(token);
Toast.makeText(context, token, Toast.LENGTH_SHORT).show();
peopleModelList.add(peopleModel);
//here i am checking my peopleModelList size is equal or not to snapshot
if(peopleModelList.size()==2)
iCallBackPeople.peopleAct(peopleModelList);
}
},peopleModel);
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
private void getToken(final CallBackGetToken callBackGetToken ,PeopleModel peopleModel) {
registrationReference.child(peopleModel.getChatWith()).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
callBackGetToken.token((String)dataSnapshot.child("refresh_token").getValue());
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}

I think you should pass through an interface(create one and implement at this class). the method inside the interface should have a string as a parameter (it will receive your peopleModel.getChatWith() ) .
Inside your if(peopleModel.getChatWith()!=null && !("".equals(peopleModel.getChatWith())))you should request your interface.
I think is a solution for your asynchronously question.

Here is my solution:
int count =0;
SortedMap<Integer,PeopleModel> sortedMap;
private void set() {
count =0;
registrationReference.child(userId).child("generated_links").addListenerForSingleValueEvent(new ValueEventListener()
{
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
peopleModelList.clear();
sortedMap = new TreeMap<>();
for(DataSnapshot snapshot : dataSnapshot.getChildren())
{
peopleModel = new PeopleModel();
peopleHashMap =(HashMap)snapshot.getValue();
peopleModel.setChatWith((String)peopleHashMap.get("chatWith"));
peopleModel.setNickname((String)peopleHashMap.get("nickname"));
peopleModel.setChatRoom(snapshot.getKey());
Log.d("kkkk","1st");
if(peopleModel.getChatWith()!=null && !("".equals(peopleModel.getChatWith())))
{
addItem(count);
count++;
}
Log.d("kkkk","3rd");
}
iCallBackPeople.peopleAct(peopleModelList);
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
private void addItem(final int index) {
registrationReference.child(peopleModel.getChatWith()).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
peopleModel.setRefresh_token((String)dataSnapshot.child("refresh_token").getValue());
Log.d("kkkk","2nd");
sortedMap.put(index, peopleModel);
// sortedMap will sort your list by key (in this case, key is integer)
// you can get peopleModelList = new ArrayList<>(sortedMap.values);
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}

Maybe I'm over simplifying it, but I feel like you should just use simple recursion.
List<People> peopleList;
int currentIndex = 0
private void myFirebaseMethodAction(person){
registerListener.onCallbacks(new ValueListener(){
onDataChanged(){
person.addStufforDoStuff();
if(peopleList.size > currentIndex + 1){
myFirebaseMethodAction(peopleList.get(++currentIndex)
}
}
onFailed(){
//handle it
}
}
}
Does that make sense?
Just saying walk the list with an index, simple.
btw above is pseduo code, don't copy verbatim lol.

how to retrieve int from firebase

private void updateScoreBreaker(){
DBref=FirebaseDatabase.getInstance().getReference().child(Gamelevel);
Query maxScore =DBref.orderByChild(SCORE).limitToLast(1);
maxScore.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
maxScoreLevel=Integer.parseInt(dataSnapshot.child(SCORE).getValue(String.class));
maxScoreName=dataSnapshot.getKey();
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
i have this error :
Cannot find local variable 'maxScoreLevel'

Seems like you haven't declared maxScoreLevel. You should declare it as a attribute of the class, so you can change it's value from the ValueEventListener.
class something {
...
Integer maxScoreLevel;
String maxScoreName;
...
private void updateScoreBreaker() {
DBref = FirebaseDatabase.getInstance().getReference().child(Gamelevel);
Query maxScore = DBref.orderByChild(SCORE).limitToLast(1);
maxScore.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
maxScoreLevel = dataSnapshot.child(SCORE).getValue(Integer.class);
maxScoreName = dataSnapshot.getKey();
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}
If corresponding reference does not exist or has no value, maxScoreLevel will be assigned with null value

Make sure that all Firebase single ValueEventsListeners finished

As mentioned in docs, it's better to fetch additional data, than nest objects in database.
According to this, how can I ensure that all data came?
I came up to this solution, but I'm not sure if this will work.
mPetsReference.addValueEventListener(new ValueEventListener() {
private List<Pair<Pet, Owner>> mData;
private long mChildrenCount;
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
mData = new ArrayList<>();
mChildrenCount = dataSnapshot.getChildrenCount();
for (DataSnapshot data : dataSnapshot.getChildren()) {
Pet pet = data.getValue(Pet.class);
mOwnersReference.child(pet.getOwnerId())
.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
mData.add(new Pair<>(pet, dataSnapshot.getValue(Owner.class)));
if (mData.size() == mChildrenCount) {
everythingCame();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
mChildrenCount--;
if (mData.size() == mChildrenCount) {
everythingCame();
}
}
});
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});

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