i have problem to get exact childs from database and add it to the list of "teams". is that possible? i can't find proper way to solve this problem. please help me.
image of my actual database structure
i want to get only values of "2" and "3", just list of all teams without members. As a result of my solution im getting all elements from all children.
i have tried sth like this:
mDatabase.child("teams").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
teamList.clear();
for(DataSnapshot snapshot : dataSnapshot.getChildren()){
teamList.add(snapshot.getValue().toString());
}
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
Use this
mDatabase.child("teams").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
teamList.clear();
for(DataSnapshot snapshot : dataSnapshot.getChildren()){
teamList.add(snapshot.getKey());
}
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
Try this:
mDatabase = _firebase.getReference("teams");
mDatabase.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot _dataSnapshot) {
teamList = new ArrayList < > ();
try {
GenericTypeIndicator < HashMap < String, Object >> _ind = new GenericTypeIndicator < HashMap < String, Object >> () {};
for (DataSnapshot _data: _dataSnapshot.getChildren()) {
HashMap < String, Object > _map = _data.getValue(_ind);
teamList.add(_map);
}
} catch (Exception _e) {
_e.printStackTrace();
}
}
#Override
public void onCancelled(DatabaseError _databaseError) { }
});
Related
I'm using Firebase realtime database. Below is the structure
Problem Statement: Over a list of "Users", I need to delete child who's having coins = 0
So far I'm stuck here
DatabaseReference deleteRef = dbref.child("Users").child("coins");
Query deleteQuery = deleteRef.orderByValue().equalTo("0");
deleteQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot child : dataSnapshot.getChildren()) {
child.getRef().setValue(null);
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException();
}
});
Any help will be appreciated :)
You need to order the list by the child coins like here:
DatabaseReference deleteRef = dbref.child("Users");
Query deleteQuery = deleteRef.orderByChild("coins").equalTo("0");
deleteQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot child : dataSnapshot.getChildren()) {
child.getRef().setValue(null);
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException();
}
});
How to get the value of this automatically without writing each one separately.
I tried this
FirebaseDatabase.getInstance().getReference().child("Orutmen").child("episodeNumber");
but it shows null value.
This one works, but I have to write for each field:
FirebaseDatabase.getInstance().getReference().child("Orutmen").child("1").child("episodeNumber");
Here is the code
m2Database = FirebaseDatabase.getInstance().getReference().child("Orutmen");
m2Database.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String value = snapshot.child("episodeNumber").getValue(String.class);
Toast.makeText(EpisodeListModel.this, value, Toast.LENGTH_SHORT).show();
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException();
}
});
You can iterate throught the children of DataSnapshot:
m2Database = FirebaseDatabase.getInstance().getReference().child("Orutmen");
m2Database.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String value;
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
value = snapshot.child("episodeNumber").getValue(String.class);
Toast.makeText(EpisodeListModel.this, value, Toast.LENGTH_SHORT).show();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException();
}
});
I figured out a way
Just added a list of strings that collects the values from the snapshot
then retrieve the value by position of item clicked >>
List<String> List = new ArrayList<>();
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
String value = snapshot.getKey();
List.add(value);
}
Toast.makeText(EpisodeListModel.this, List.get(position), Toast.LENGTH_SHORT).show();
Hy, I'm writing an application that has to get specific data from firebase using the position of the item in the listView. My problem is that I have no idea how to take it this item on firebase.
For all child of Torneo I have to control all the nameCreator.
I have tried this:
public Boolean RegisterUser(Data data, final int position, final Context c){
boolean registration;
final ArrayList<String> Creator = new ArrayList<>();
databaseReference.orderByChild("Tornei").equalTo(Integer.toString(position)).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot datas: dataSnapshot.getChildren()){
Creator.add(data.child("nameCreator").getValue().toString());
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
if(Creator.equals(data.getNameCreator())){
registration = false;
}else{
registration = true;
}
return registration;
}
Data is a class with some getter and setter that I have created.
position is the position of the element on the list view.
Thanks for answers.
Change the following:
databaseReference.orderByChild("Tornei").equalTo(Integer.toString(position)).addListenerForSingleValueEvent(new ValueEventListener() {
into this:
databaseReference.child("Tornei").addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot datas: dataSnapshot.getChildren()){
Creator.add(datas.child("nameCreator").getValue().toString());
if(Creator.equals(data.getNameCreator())){
registration = false;
}else{
registration = true;
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Then you will be able to loop and retrieve the value of nameCreator
It's easy.
【Step 1 | Get Snapshot Data and Save in Global Variable】
DatabaseReference rootReference = FirebaseDatabase.getInstance().getReference();
DatabaseReference fruitsReference = rootReference.child("fruits");
DataSnapshot fruitsData;
#Override
protected void onStart() {
super.onStart();
fruitsReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshots) {
fruitsData = dataSnapshots;
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
【Step 2 | Find Your Target Position through the Loop】
public void onClick(View view) {
int index = 0;
for (DataSnapshot childSnapshot : fruitsData.getChildren()) {
if (index == 1) { //your target position
DatabaseReference currentFruitReference = childSnapshot.getRef();
currentFruitReference.setValue("peach"); //do whatever you want
}
index++;
}
}
databaseReference = FirebaseDatabase.getInstance().getReference("/sample");
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
Log.d(TAG, "onDataChange: dataSnapshot "+dataSnapshot.getValue());
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
I'm new to android app development and firebase as well. i m fetching data from sample node and getting DataSnapshot value like below.
{size=[Small, Large, Ex-Large], type=[Type 1, Type 2], color=[Red, Green, Blue], category=[T-Shirt, Jeans, Sweater]}
need some expect help, any suggestion will greatly appreciated.
Thanks
To retrieve values separately, you can use a code like this:
databaseReference.child("category").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (int i=0;i<3;i++) {
// category is an ArrayList you can declare above
category.add(dataSnapshot.child(String.valueOf(i)).getValue(String.class));
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) { // Do something for this
}
});
Similarly you can add values of other nodes in your other ArrayLists, just by changing the value of Childs in this code.
Firebase has no native support for arrays. If you store an array, it really gets stored as an "object" with integers as the key names.
// we send this
['hello', 'world']
// Firebase stores this
{0: 'hello', 1: 'world'}
Best Practices: Arrays in Firebase
// TRY THIS
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
youNameArray = new ArrayList<>();
for (DataSnapshot snapshot : dataSnapshot.getChildren()){
String data = snapshot.getValue(String.class);
youNameArray.add(data);
}
Log.v("asdf", "First data : " + youNameArray.get(0));
}
Something like this:
databaseReference = FirebaseDatabase.getInstance().getReference("/sample");
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot sampleSnapshot: dataSnapshot.getChildren()) {
Log.d(TAG, "onDataChange: sampleSnapshot "+sampleSnapshot.getKey()+" = "+sampleSnapshot.getValue());
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
throw databaseError.toException(); // don't ignore errors
}
});
The difference is that in my answer I loop over dataSnapshot.getChildren() to get each individual sample snapshot. The sampleSnapshot.getValue() call should return a List.
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference refence = database.getReference();
refence.addValueEventListener(new ValueEventListener()
{
#Override
public void onDataChange(DataSnapshot snapshot) {
// TODO Auto-generated method stub
ArrayList array= new ArrayList<>();
for (DataSnapshot ds : snapshot.getChildren()){
String data = ds.getValue().toString();
array.add(data);
}
System.out.println(array);
}
#Override
public void onCancelled(DatabaseError error) {
// TODO Auto-generated method stub
}
});
In my case String.class does not work instead .toString method works
String data = ds.getValue().toString();
FirebaseDatabase.getInstance().getReference("Block").addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot snap : dataSnapshot.getChildren()) {
if(snap.getKey().equals(myUID)){
FirebaseDatabase.getInstance().getReference("Block").child(myUID).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot snap : dataSnapshot.getChildren()) {
if(snap.getKey().equals(list.get(position).getUid())){
FirebaseDatabase.getInstance().getReference("Block").child(myUID).child(list.get(position).getUid()).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot snap : dataSnapshot.getChildren()) {
if(snap.getValue().equals("1")){
call_method();
}else{
//code...
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
} else {
call_method();
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
} else {
call_method();
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
This code works well, but it is very long so I am asking for the best way to write it ?
I want to check firstly if Block node has child equals to my UID if it is true then I want to check if my UID has child equals to specific UID if it is true then I want to get the value of block which is 0 in this example
How can I do that ? Thank you very much.
Just traverse to the path specified using child. You will get no data if the path doesn't exist.
FirebaseDatabase.getInstance().getReference("Block")
.child("MyUUID")
.child("specificUUID")
.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(dataSnapshot.exists()) {
// ... Do something
} else {
call_method();
}
// ... Other code
}
Try this:
Firebaseuser user=FirebaseAuth.getInstance().getCurrentUser();
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Block");
ref.child(user.getUid()).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(dataSnapshot.exist()){
//checks first uid
if(dataSnapshot.hasChild(seconduid){
//checks if seconduid is there
for(DataSnapshot datas:dataSnapshot.getChildren()){
String blocks=datas.child("block").getValue().toString();
}
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
This will check the first uid if(dataSnapshot.exist()) after that it will check if that uid node has the second uid that you provide if(dataSnapshot.hasChild(seconduid){ then you will iterate and get the node block