I want to delete the particular child of a child in firebase realtime database.
I have added a picture of my database.
I want to remove the highlighted child.
You can try this code.
Query query = myRef.child("Purchase_Request").orderByChild("Chimney_Purchase");
query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot snap: dataSnapshot.getChildren()) {
if(snap.getKey().equals("your_key")) {
snap.getRef().removeValue();
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
Log.e(TAG, "onCancelled", databaseError.toException());
}
});
Related
Hello all i have a my fire-base structure like this
Firebase Database
I have an array list inside an node in fire-base , I need to loop through this list and jump to each ID to get information i need like the database photo shows.
what I've tried so far
public static void checkIfCurrentUserLiked(final HomeFragment.PostsViewHolder postsViewHolder, String postKey) {
userID = Objects.requireNonNull(FirebaseAuth.getInstance().getCurrentUser()).getUid();
likesRef = FirebaseDatabase.getInstance().getReference().child("likes");
postsRef = FirebaseDatabase.getInstance().getReference().child(postKey);
postsRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.hasChild("likes")) {
for (DataSnapshot ds : dataSnapshot.child("likes").getChildren()) {
likesRef.child(Objects.requireNonNull(ds.getValue()).toString())
.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot snapshot) {
Like like = snapshot.getValue(Like.class);
if (like != null && like.getLikedUserID().equals(userID)) {
postsViewHolder.likesImage.setImageResource
(R.drawable.ic_item_home_post_like_filled);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) { }
});
}
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) { }
});
}
i have no error , just nothing happens , data are not fetched as expected
Change this:
postsRef = FirebaseDatabase.getInstance().getReference().child(postKey);
into this:
postsRef = FirebaseDatabase.getInstance().getReference().child("posts").child(postKey);
According to your database, you have node posts before the postKey, therefore you need to add it when referencing to a location.
I need to do join operation for data using the unique key provided by the Firebase database.Table habitat is created under the unique key of snake table.And also need to retrive data for list view or recyclerview.
databaseSnake = FirebaseDatabase.getInstance().getReference()
.child("snake")
.orderByKey()
.addValueEventListener(
new ValueEventListener()
{
#Override
public void onDataChange(DataSnapshot dataSnapshot)
{
for (DataSnapshot child : dataSnapshot.getChildren())
{
// HERE CORRESPONDS TO JOIN
DatabaseReference Databasesnake = FirebaseDatabase.getInstance().getReference()
.child("habitat")
.orderByKey()
.addValueEventListener(
new ValueEventListener()
{
#Override
public void onDataChange(DataSnapshot dataSnapshot)
{
// repeat!!
}
#Override
public void onCancelled(DatabaseError databaseError)
{
}
}
}
}
#Override
public void onCancelled(DatabaseError databaseError)
{
}
I want to reach second child directly , first child name is random.
I want to reach kullaniciadi child;
https://i.hizliresim.com/dO58mp.png
try this:
DatabaseReference db=FirebaseDatabase.getInstance().getReference().child("Kullanicilar");
db.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot data: dataSnapshot.getChildren()){
String kullaniciad=data.child("kullaniciadi").getValue().toString();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Here you have the datasnapshot at child Kullanicilar. Then you iterate inside of it and get the child kullaniciadi that is under the pushids
Hello Everyone I am using firebase database in my app. I am able to add data to database. Now I want to implement search in my app, I have two option for search users,
1)Blood Group
2)User Area
I am able to get data as per blood group selection, but I don't know how can I fetch data with blood group and area. (Multiple Selection Filter)
Now if the user will select 'A+' as blood group from spinner and select Area 'ABC'
Then result would come as Users with 'A+' blood group and 'ABC' area.
search_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
System.out.println("Default Selected"+sel_blood_group);
mFirebaseDatabase.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
//Your Logic here
for (DataSnapshot eventSnapshot : dataSnapshot.getChildren()) {
UserRegisterModel mModel = eventSnapshot.getValue(UserRegisterModel.class);
// Log.e("DATA" ,""+ mModel.getName());
}
Query chatRoomsQuery = mFirebaseDatabase.orderByChild("blood_group").equalTo(sel_blood_group);
chatRoomsQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
// dataSnapshot is the "issue" node with all children with id 0
for (DataSnapshot issue : dataSnapshot.getChildren()) {
// do something with the individual "issues"
UserRegisterModel mModel = issue.getValue(UserRegisterModel.class);
Log.e("QUERY DATA" ,""+ mModel.getName());
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Log.e("DATA" ,""+ chatRoomsQuery.toString());
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
});
Firebase RealTime Database does not support multiple where clauses. So try to query with one filter and then filter the next one programatically.
search_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
System.out.println("Default Selected"+sel_blood_group);
System.out.println("Default Selected"+sel_area);
mFirebaseDatabase.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
//Your Logic here
for (DataSnapshot eventSnapshot : dataSnapshot.getChildren()) {
UserRegisterModel mModel = eventSnapshot.getValue(UserRegisterModel.class);
// Log.e("DATA" ,""+ mModel.getName());
}
Query chatRoomsQuery = mFirebaseDatabase.orderByChild("blood_group").equalTo(sel_blood_group);
chatRoomsQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
// dataSnapshot is the "issue" node with all children with id 0
for (DataSnapshot issue : dataSnapshot.getChildren()) {
// do something with the individual "issues"
UserRegisterModel mModel = issue.getValue(UserRegisterModel.class);
if(mModel.getArea().equals(sel_area))
Log.e("QUERY DATA" ,""+ mModel.getName());
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Log.e("DATA" ,""+ chatRoomsQuery.toString());
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
});enter code here
You can make userName to be added only once using the following method. I have assumed that you are storing the user details in UserRegisterModel class. Please take care of the DatabaseReferences as I have used what you have mentioned and I am not aware of your Database structure.
Query chatRoomsQuery = mFirebaseDatabase.orderByChild("User_Name").equalTo(userRegisterModel.getUserName());
chatRoomsQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
Log.e("UserAlready Registered");
}
else
{
mFirebaseDatabase.push().setValue(userRegisterModel);;
Log.i("User added Successfully");
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
I have not tested the code but I think it will work! :)
I want to apply query in firebase as
"Those Students Who Are Having More Marks Then 70 in tenthP as well as in twelveP" and then show list of their names in list view.
This is I am using query in one child :
DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
Query query = reference.child("users").orderByChild("tenth").startAt("70").endAt("100");
query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
Toast.makeText(FilterStudentsActivity.this,"Yes Exist",Toast.LENGTH_LONG).show();
// dataSnapshot is the "issue" node with all children with id 0
for (DataSnapshot issue : dataSnapshot.getChildren()) {
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});