Develop Reference

Cannot get reference to the automatically generated key in Firebase in Android Studio

I am making an android app with Firebase Realtime Database. This is my database:
{
"Data" : {
"UyhzVqsz1BVFKoePa2NEmlPFu382" : {
"Budget_Income" : {
"bbbb" : {
"stData1" : "bbbb",
"stData2" : "bb",
"stData3" : "bb",
"stData4" : "1000"
}
},
"Entry_Income" : {
"bbbb" : {
"-MYk3lQuK4X6zcIZtHRD" : {
"stData1" : "bbbb",
"stData2" : "20 Apr 2021",
"stData3" : "ddd",
"stData4" : "500"
}
}
}
}
}
}
I am trying to get the data back in RecyclerView in one activity with the following reference:
myfire = FirebaseDatabase.getInstance();
myRef = myfire.getReference().child("Data").child(strUID).child("Entry_Income");
String uid = myRef.child(title).push().getKey(); // title is reference to "bbb"
myRef.child(uid).addValueEventListener(new ValueEventListener() {
..........................
The data is empty.
I am able to get one child by the following code:-
myRef = myfire.getReference().child("Data").child(strUID).child("Entry_Income").child(title);
myRef.child("-MYk3lQuK4X6zcIZtHRD").addValueEventListener(new ValueEventListener() {
.............
But I want all children like "-MYk3lQuK4X6zcIZtHRD" in my RecyclerView.
My Issue I think the reference to push id is wrong.
A solution with example needed.
full code*
myRef = myfire.getReference().child("Data").child(strUID).child("Budget_Income");
//-------------------------------
//------------------------------------------
Toast.makeText(MainActivity.this, "Please Wait a While !", Toast.LENGTH_LONG).show();
//-------------------------
options1 = new FirebaseRecyclerOptions.Builder<category>()
.setQuery(myRef, category.class)
.build();
final FirebaseRecyclerAdapter<category, holder1> adapter = new FirebaseRecyclerAdapter<category, holder1>(options1) {
#SuppressLint("SetTextI18n")
#Override
protected void onBindViewHolder(#NotNull final holder1 holder, final int i, #NotNull final category passage) {
final String title = getRef(i).getKey();
category=title;
assert title != null;
myRef = myfire.getReference().child("Data").child(strUID).child("Budget_Income");
myRef.child(title).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.getValue() == null) {
Toast.makeText(getApplicationContext(), "Data Not Available", Toast.LENGTH_LONG).show();
} else {
final String stData1 = (Objects.requireNonNull(dataSnapshot.child("stData1").getValue())).toString();
final String stData2 = (Objects.requireNonNull(dataSnapshot.child("stData2").getValue())).toString();
final String stData3 = (Objects.requireNonNull(dataSnapshot.child("stData3").getValue())).toString();
final String stData4 = (Objects.requireNonNull(dataSnapshot.child("stData4").getValue())).toString();
category basic = new category(stData1, stData2, stData3, stData4);
holder.tvOne.setText(stData1);
holder.tvTwo.setText(stData4);
}
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
throw error.toException(); // never ignore errors
}
});
myRef = myfire.getReference().child("Data").child(strUID).child("Entry_Income").child(title);
String uid = myRef.push().getKey();
assert uid != null;
myRef.child(uid).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.getValue() == null) {
Toast.makeText(getApplicationContext(), "Data Not Available", Toast.LENGTH_LONG).show();
} else {
final String stData1 = (Objects.requireNonNull(dataSnapshot.child("stData1").getValue())).toString();
final String stData2 = (Objects.requireNonNull(dataSnapshot.child("stData2").getValue())).toString();
final String stData3 = (Objects.requireNonNull(dataSnapshot.child("stData3").getValue())).toString();
final String stData4 = (Objects.requireNonNull(dataSnapshot.child("stData4").getValue())).toString();
category basic = new category(stData1, stData2, stData3, stData4);
holder.tvThree.setText(stData3);
holder.tvFour.setText(stData4);
}
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
throw error.toException(); // never ignore errors
}
});
}
#NonNull
#Override
public holder1 onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.item1, parent, false);
return new holder1(v);
}
};
userlist.setAdapter(adapter);
adapter.startListening();
}
}
Category Class code*
public class category {
private String stData1;
private String stData2;
private String stData3;
private String stData4;
public category() {
}
public category(String stData1, String stData2, String stData3, String stData4) {
this.stData1 = stData1;
this.stData2 = stData2;
this.stData3 = stData3;
this.stData4 = stData4;
}
public String getStData1() {
return stData1;
}
public void setStData1(String stData1) {
this.stData1 = stData1;
}
public String getStData2() {
return stData2;
}
public void setStData2(String stData2) {
this.stData2 = stData2;
}
public String getStData3() {
return stData3;
}
public void setStData3(String stData3) {
this.stData3 = stData3;
}
public String getStData4() {
return stData4;
}
public void setStData4(String stData4) {
this.stData4 = stData4;
}
}
This is the way to get the data:
myRef = myfire.getReference().child("Data").child(strUID).child("Entry_Income").child(title);
myRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot data : dataSnapshot.getChildren()) {
String value = data.child("stData4").getValue(String.class);
}
holder.tvThree.setText(value);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
throw databaseError.toException(); // never ignore errors
}
});
But the problem is that recycler view is showing more items at bottom without values on scroll.

According to my last comment, please see below a solution for getting data from the following reference:
rootRef -> Data -> strUID -> Entry_Income
No matter if there is a single child ("bbbb"), or multiple children under the "Entry_Income" node and Log the data of stData1 out in the logcat. You can similarly do the same thing for the other stData2, stData3, stData4 fields. So please try the code below:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference entryIncomeRef = rootRef.child("Data").child(uid).child("Entry_Income");
entryIncomeRef.get().addOnCompleteListener(new OnCompleteListener<DataSnapshot>() {
#Override
public void onComplete(#NonNull Task<DataSnapshot> task) {
if (task.isSuccessful()) {
for (DataSnapshot titleSnapshot : task.getResult().getChildren()) {
for (DataSnapshot categorySnapshot : titleSnapshot.getChildren()) {
category cat = categorySnapshot.getValue(category.class);
Log.d(TAG, cat.getStData1());
}
}
} else {
Log.d(TAG, task.getException().getMessage()); //Don't ignore potential errors!
}
}
});
The key for solving this issue is to loop through the "DataSnapshot" object twice, using a call to ".getChildren()" method. However, this solution will only work if you create your own adapter. It won't work with the "FirebaseRecyclerAdapter". If you need to use the Firebase-UI library, then I recommend you duplicate the data by adding all "bbbb" children into a single node. This practice is called "denormalization" and it's a common practice when it comes to Firebase. For a better understanding, I recommend you see this video, Denormalization is normal with the Firebase Database.
That being said, create a new reference to the newly created node, and pass that object to the FirebaseRecyclerOptions.Builder's "setQuery()" method. That's it!

I think the data at that point indeed empty. Try setting a value with that "new id" and then add your listener.
myfire = FirebaseDatabase.getInstance();
myRef = myfire.getReference().child("Data").child(strUID).child("Entry_Income");
String uid = myRef.child(title).push().getKey(); // title is reference to "bbb"
//note that this line edited: we are setting a value for the "new" key
myRef.child(uid).setValue(yourData);
myRef.child(uid).addValueEventListener(new ValueEventListener() {
...
}

display a String recover from firebase database in a textview

I have this code which retrieves the information I need from the firebase database:
private void getname(){
DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
Query lastQuery = ref.child("ride_info").orderByKey().limitToLast(1);
lastQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()){
String value0_float = ds.child("pickup").child("name").getValue(String.class);
pickupName = String.valueOf(value0_float);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
and i have this:
public String getPickupName() {
getname();
String s = String.valueOf(pickupName);
return s;
}
All of the above code is in the RideObject class.
This is the code there is in CardRequestAdapter Class to display the String in the textview mPickupName:
public View getView(int position, View convertView, ViewGroup parent){
RideObject card_item = getItem(position);
if (convertView == null){
convertView = LayoutInflater.from(getContext()).inflate(R.layout.item__card_request, parent, false);
}
TextView mDistance = convertView.findViewById(R.id.distance);
TextView mTime = convertView.findViewById(R.id.time);
CircularProgressBar mProgressBar = convertView.findViewById(R.id.circularProgressBar);
mDistance.setText(card_item.getPickupName());
mTime.setText(card_item.getCalculatedTime() + " min");
final Handler ha=new Handler();
ha.postDelayed(new Runnable() {
#Override
public void run() {
//call function
card_item.setTimePassed(card_item.getTimePassed() + (float)0.5);
mProgressBar.setProgress(card_item.getTimePassed());
if(card_item.getTimePassed() > 100){
items.remove(card_item);
notifyDataSetChanged();
}
ha.postDelayed(this, 50);
}
}, 50);
return convertView;
}
}
The problem I have is that I cannot get the name I got from the Firebase database. Why is nothing displayed in the text view?

Data is loaded from Firebase asynchronously, since it may take some time. If you set some breakpoints or add some logging you'll likely see that mDistance.setText(card_item.getPickupName()); runs before pickupName = String.valueOf(value0_float), which means you're setting an empty string into the text view.
The rule to fix/prevent this is simple: any code that needs data from the database needs to be inside onDataChange or be called from there.
So something like:
DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
Query lastQuery = ref.child("ride_info").orderByKey().limitToLast(1);
lastQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()){
String value0_float = ds.child("pickup").child("name").getValue(String.class);
pickupName = String.valueOf(value0_float);
mDistance.setText(pickupName);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException(); // never ignore errors
}
});
Also see:
getContactsFromFirebase() method return an empty list

Firebase Database unable to retrieve value

I am unable to change the text of multiple TextView to the values retrieved from Firebase Realtime Database.
My database looks like: Database
My current code is:
public class SearchResult extends AppCompatActivity {
TextView searchResultHSPName,searchResultHSPStatus, searchResultHSPType,searchResultHSPRating;
Button messageButton;
private static final String TAG = "SearchResult";
DatabaseReference rootReference;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search_result);
searchResultHSPName = (TextView) findViewById(R.id.hspNameSearchResultTextView);
searchResultHSPType = (TextView) findViewById(R.id.hspTypeSearchResultTextView);
searchResultHSPRating = (TextView) findViewById(R.id.hspRatingSearchResultTextView);
searchResultHSPStatus = (TextView) findViewById(R.id.hspStatusSearchResultTextView);
//take the searched name from searchFunction and query db for the user details
Intent intent = getIntent();
final String searchedHSPName = intent.getExtras().getString("SearchFunctionMessage");
rootReference = FirebaseDatabase.getInstance().getReference();
DatabaseReference userReference = rootReference.child("HSPUsers");
userReference.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
HSPUsers user = snapshot.getValue(HSPUsers.class);
String userName = user.HSPName;
if(userName == searchedHSPName){
searchResultHSPName.setText(userName);
searchResultHSPStatus.setText(user.HSPStatus);
searchResultHSPRating.setText(user.HSPRating);
searchResultHSPType.setText(user.HSPType);
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}
And my HSPUsers class is:
public class HSPUsers {
//HSP user contains 4 fields of data UserName, Status,Type,Rating
public String HSPName,HSPStatus, HSPType,HSPRating;
//constructor for datasnapshot
public HSPUsers(){
}
public HSPUsers(String username, String status, String type, String rating){
this.HSPName=username;
this.HSPStatus=status;
this.HSPType=type;
this.HSPRating=rating;
}
//get and set methods
public String getHSPUserName() {
return HSPName;
}
public void setHSPUserName(String HSPUserName) {
this.HSPName = HSPUserName;
}
public String getHSPUserStatus() {
return HSPStatus;
}
public void setHSPUserStatus(String HSPUserStatus) {
this.HSPStatus = HSPUserStatus;
}
public String getHSPUserType() {
return HSPType;
}
public void setHSPUserType(String HSPUserType) {
this.HSPType = HSPUserType;
}
public String getHSPUserRating() {
return HSPRating;
}
}
public String getHSPUserRating() {
return HSPRating;
}
}
Ideally, i would like to change the textViews to the user's Name/Status/Rating/Type. However, there has been no change to the textviews and i am left with UnchangedTextViews
Would appreciate any advice on how to change the TextViews to the HSPName/rating/Status/type?
Thank you in advance for any advice.

not be able to retrieve firebase data using addValueEventListener

I am trying to retrieve firebase data using addValueEventListener, but unfortunately i am not be able to get right data.
I have New_Deal_List.java class, and in this class i want to retrieve `public class New_Deal_List extends AppCompatActivity {
ListView lvDealList;
List<NewDeal_Database> dealList;
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference("Expert");
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.new__deal__list);
lvDealList = (ListView)findViewById(R.id.lvDealList);
dealList = new ArrayList<>();
}
#Override
protected void onStart() {
super.onStart();
rootRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
dealList.clear();
for(DataSnapshot dealSnapshot : dataSnapshot.getChildren()){
NewDeal_Database info = dealSnapshot.getValue(NewDeal_Database.class);
dealList.add(info);
}
DealList adapter = new DealList( New_Deal_List.this,dealList);
lvDealList.setAdapter(adapter);
}
#Override
public void onCancelled(DatabaseError databaseError) {
Toast.makeText(New_Deal_List.this,"Databse error",Toast.LENGTH_SHORT).show();
}
});
}
I am adding data through New_Deal.java by this method
private void AddNewDeal(){
int DealName = Integer.parseInt(etDealName.getText().toString());
String NewDealCategory = etNewDealCategory.getText().toString();
String DishName = etDishName.getText().toString();
String DealDescription = etDealDescription.getText().toString();
if(TextUtils.isEmpty(etDishName.getText().toString()) || TextUtils.isEmpty(etNewDealCategory.getText().toString()) || TextUtils.isEmpty(etDishName.getText().toString()) || TextUtils.isEmpty(etDealDescription.getText().toString())){
Toast.makeText(this,"All fileds must be filled.",Toast.LENGTH_SHORT).show();
}else{
DealId = keyRefrence.push().getKey();
//firebaseDatabase data = new firebaseDatabase(DealName,NewDealCategory,DishName,DealDescription);
//Contact_Info info = new Contact_Info( DealName, NewDealCategory, DealDescription);
NewDeal_Database info = new NewDeal_Database(DealName,NewDealCategory, DishName, DealDescription); keyRefrence.child(Cooker_Deal).child(DealId).child(Deal).setValue(info);
Toast.makeText(this,"Information Added",Toast.LENGTH_SHORT).show();
Intent intent = new Intent(New_Deal.this,New_Deal_Time.class);
startActivity(intent);
}
}
I am setting value using this NewDeal_Databse.java
public NewDeal_Database(int DealName,String NewDealCategory, String DishName, String DealDescription){
this.DealName = DealName;
this.NewDealCategory = NewDealCategory;
this.DishName = DishName;
this.DealDescription = DealDescription;
}
public int getDealName() {
return DealName;
}
public String getNewDealCategory() {
return NewDealCategory;
}
public String getDishName() {
return DishName;
}
public String getDealDescription() {
return DealDescription;
}
Also i DealList.java for array adapter
public class DealList extends ArrayAdapter <NewDeal_Database> {
private Activity context;
private List<NewDeal_Database> dealList;
public DealList(Activity context, List<NewDeal_Database> dealList){
super(context, R.layout.list_layout, dealList);
this.context = context;
this.dealList = dealList;
}
#NonNull
#Override
public View getView(int position, #Nullable View convertView, #NonNull ViewGroup parent) {
LayoutInflater inflater = context.getLayoutInflater();
View listViewItem = inflater.inflate(R.layout.list_layout,null,true);
TextView tvDealName = (TextView)listViewItem.findViewById(R.id.tvDealNamelayout);
TextView tvNewDealCategory = (TextView)listViewItem.findViewById(R.id.tvNewDealCategorylayout);
NewDeal_Database info = dealList.get(position);
tvDealName.setText(String.valueOf(info.getDealName()));
tvNewDealCategory.setText(info.getNewDealCategory());
return listViewItem;
}
}
I get these on values on output
Output the data
I this is firebase databse snapshot
firebase datasbe snapshot
updated firebase databse snapshot
Updated output
Problem solved using this code:
#Override
protected void onStart() {
super.onStart();
//dealList.clear();
rootRef.child(id).child(Cooker_Deal).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot dealSnapshot : dataSnapshot.getChildren()){
for(DataSnapshot datas : dealSnapshot.getChildren()){ //
NewDeal_Database info = datas.getValue(NewDeal_Database.class);
count++;
if(count>3){
dealList.add(info);
count=0;
}
}
}
DealList adapter = new DealList( New_Deal_List.this,dealList);
lvDealList.setAdapter(adapter);
adapter.notifyDataSetChanged();
}

I think its nested too much but to answer your question, you need to remove this from your code:
dealList.clear();
and add it outside of the addValueEventListener()
like this:
protected void onStart() {
super.onStart();
dealList.clear();
rootRef.addValueEventListener(new ValueEventListener() {
Edit:
#Override
protected void onStart() {
super.onStart();
dealList.clear();
rootRef.child(expertId).child("Cooker Deals").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot dealSnapshot : dataSnapshot.getChildren()){
for(DataSnapshot datas : dealSnapshot.getChildren(){
NewDeal_Database info = datas.getValue(NewDeal_Database.class);
dealList.add(info);
}
DealList adapter = new DealList( New_Deal_List.this,dealList);
lvDealList.setAdapter(adapter);
adapter.notifydatasetchanged();
}

Assuming that faum-expert nide is a direct child of your Firebase database, to get that data, please use the following code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference ref = rootRef.child("faum-expert").child("Expert").child(expertId).child("Cooker Deals");
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String dealName = ds.child("Deals Information").child("dealName").getValue(String.class);
String newDealCategory = ds.child("Deals Information").child("newDealCategory").getValue(String.class);
Log.d("TAG", dealName + " / " + newDealCategory);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
ref.addListenerForSingleValueEvent(eventListener);
The output will be:
4567 / kagj
But pay atention, the fields inside your model class are first letter uppercase and in your database are first letter lowercase. To solve this, add the following annotations in front of your fields like this:
#PropertyName("dealName")
private String DealName;
#PropertyName("newDealCategory")
private String NewDealCategory;
#PropertyName("dishName")
private String DishName;
#PropertyName("dealDescription")
private String DealDescription;

How to display data in a recyclerview using FirebaseUI?

I am new to firebase and I am in love with this real-time database thing.
However, I am not sure how to display nested data in a recycled view.
Following is my database structure :-
I want to display the data at 0,1,2...The data consist of information about different books.
This is what I have tried so far:-
private void getSelectedBooks() {
FirebaseRecyclerAdapter<BooksInfo, BooksViewHolder> adapter = new FirebaseRecyclerAdapter<BooksInfo, BooksViewHolder>(
BooksInfo.class,
R.layout.book_list,
BooksViewHolder.class,
nextOrder.child(String.valueOf(index))
) {
#Override
protected void populateViewHolder(BooksViewHolder viewHolder, final BooksInfo model, final int position) {
Log.d("BOOKDETAILS",model.getTitle());
// viewHolder.setTitle(model.getTitle());
// viewHolder.setISBN(model.getISBN());
// viewHolder.setDiscount(model.get());
// viewHolder.setQty(model.getQuantity());
// viewHolder.setPrice(model.getPrice());
// viewHolder.setGrossValue(model.get);
// viewHolder.setNetValue(model.get);
viewHolder.mView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
DatabaseReference ref = getRef(position);
String key = ref.getKey();
Toast.makeText(AddOrderActivity.this, key, Toast.LENGTH_SHORT).show();
// getRetailerInfo(key);
}
});
}
};
selectedBookRecyclerView.setAdapter(adapter);
mDatabase.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.child(String.valueOf(index)).exists()) {
// run some code
// DisableProgress();
} else {
// DisableProgress();
// Toast.makeText(RetailerActivity.this, "No retailers to display", Toast.LENGTH_SHORT).show();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
Here DatabaseReference nextOrder = mDatabase.child(userId).child("order_details").child(String.valueOf(index));
Any help or suggestion is appreciated.Thank you.