Develop Reference

How to search through data in firebase android from given structure

I want to search through data in firebase like here:
I have already tried, but it not works
//Query query = FirebaseDatabase.getInstance().getReference(uid).orderByChild("title").startAt(editable.toString()).endAt(editable.toString()+"\uf888");
DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("categoreis");
Query query = FirebaseDatabase.getInstance().getReference("categoreis").limitToFirst(4).orderByChild("image");
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
list.clear();
for (DataSnapshot data:dataSnapshot.getChildren())
{
for (DataSnapshot ds:data.child("SubAccessories").getChildren())
{
for (DataSnapshot ds1:ds.getChildren())
{
//Log.d("checkData1",ds1.toString());
//Log.d("checkData1",ds1.child("image").getValue(String.class));
}
}
}

If you want to get the image as I see in your question, please use the following lines of code but assuming that the categories node is a direct child of your Firebase database root:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference ref = rootRef.child("categories/Accessories/SubAccessories/Accessories/Grab Bar");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String image = dataSnapshot.child("image").getValue(String.class);
Log.d("TAG", image);
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
ref.addListenerForSingleValueEvent(valueEventListener);
According to your comment, you should loop through the second Accessories node using getChildren() method like this:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference ref = rootRef.child("categories/Accessories/SubAccessories/Accessories");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String image = dataSnapshot.child("image").getValue(String.class);
Log.d("TAG", image);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
ref.addListenerForSingleValueEvent(valueEventListener);

Retrieving Data objects from Child in Firebase Android For a Logged in User

I've been trying to retrieve just the child data from here but when i debug it shows null on each object, I'm not sure why, please help.
I've followed some instructions here on Stack overflow but i can't seem to get a solution.
My data on firebase looks like this:
Here is my code:
FirebaseAuth mFirebaseAuth = FirebaseAuth.getInstance();
FirebaseUser mFirebaseUser = mFirebaseAuth.getCurrentUser();
DatabaseReference dbRef = FirebaseDatabase.getInstance().getReference().child("the-root-db");
DatabaseReference mFirebaseDbReferenceCurrentUser = dbRef.child(mFirebaseUser.getUid());
DatabaseReference userSettingTable = mFirebaseDbReferenceCurrentUser.child("UserSetting");
userSettingTable.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot userSettingFromDb : dataSnapshot.getChildren()) {
mDbPrice = (String) userSettingFromDb.child("currencyPrice").getValue();
mDbCurrencyId = (String) userSettingFromDb.child("currencyId").getValue();
mDbUserTrackPrice = (String) userSettingFromDb.child("userSettingCurrencyValue").getValue();
break;
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
Log.d("Query Db", databaseError.toString());
}
});

Since you're attaching a ValueListener to a specific node, you will get a DataSnapshot with only that node. This means you don't need to loop over its children.
userSettingTable.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
mDbPrice = dataSnapshot.child("currencyPrice").getValue(String.class);
mDbCurrencyId = dataSnapshot.child("currencyId").getValue(String.class);
mDbUserTrackPrice = dataSnapshot.child("userSettingCurrencyValue").getValue(String.class);
}

Followers structure firebase android

I want to implement followers functionality in my android application. 'First' image refers to the list of user i followed. 'second' image have all ids of all the posts that users post and 'third' image havin post details. all i want to do is to load only the post of those users that i've followed.
What i am doing is, i get emails from followers node and by using indexed recyclerview i load the data but its not working because recyclerview is not getting dynamic reference. Any sugested solution ?
first
second
third

In order to achieve this, you need to query your database for three times like this:
FirebaseUser firebaseUser = firebaseAuth.getCurrentUser();
String userEmail = firebaseUser.getEmail();
String encodedUserEmail = userEmail.replace(".", ",");
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference userEmailFromFollowersRef = rootRef.child("followers").child(encodedUserEmail);
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String followerEmail = ds.getKey();
DatabaseReference my_postsRef = rootRef.child("my_posts").child(followerEmail);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot dSnapshot : dataSnapshot.getChildren()) {
String postId = dSnapshot.getKey();
DatabaseReference postsRef = rootRef.child("posts").child(postId);
ValueEventListener vel = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot child : dataSnapshot.getChildren()) {
String postText = child.child("postText").getValue(String.class);
Log.d("TAG", postText);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
postsRef.addListenerForSingleValueEvent(vel);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
my_postsRef.addListenerForSingleValueEvent(valueEventListener);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
userEmailFromFollowersRef.addListenerForSingleValueEvent(eventListener);

Android Studio Firebase "No Such instance field" error

I am using Firebase for my Android app. In the code below,
DatabaseReference rootReference = FirebaseDatabase.getInstance().getReference();
matchReference = rootReference.child("tournaments");
userReference = rootReference.child("Users").child(deviceID);
userReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot snapshot : dataSnapshot.getChildren()) {
if(snapshot.child(matchList.get(position).getId()).exists()) {
//If the user has Starred this game
isStarred = true;
} else { isStarred = false; }
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
I get a "No Such instance field" error in the userReference field. When I debug it, it gives me the correct database path, but it does not enters the addValueEventListener function.
My database looks like
and another child called "starredGames" will be added in my code.
Why is it giving me the error?

The correct way of getting the value of your deviceID is:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference deviceIDRef = rootRef.child("Users").child("6610609cfc2c7945");
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String deviceID = dataSnapshot.child("deviceID").getValue(String.class);
Log.d("TAG", deviceID);
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
deviceIDRef.addListenerForSingleValueEvent(eventListener);

How can I give access to certain objects in Firebase database based on id

I have this data structure:
The red arrows points at animal IDs, and the blue arrow points at user IDs. Every user have one or many animals.
I have tried different methods for showing only the animals that have id that is stored in the current user node.
Example: If I have UID = 48onHXIxgDP465j5WW16oo7psNm2 (the first one in "users") I want to show the data from: "dog2" and "dog3".
Now iIhave the following code that gets snapshot from the "animals" node in the database, and then gets data from every child.
myAnimalRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
list = new ArrayList<AnimalCard>();
for(DataSnapshot dataSnapshot1 :dataSnapshot.getChildren()){
AnimalCard value = dataSnapshot1.getValue(AnimalCard.class);
AnimalCard animal = new AnimalCard();
String name = value.getName();
int age = value.getAge();
String url = value.getUrl();
animal.setName(name);
animal.setAge(age);
animal.setUrl(url);
list.add(animal);
}
recyclerViewSetAdapter();
progressDialog.dismiss();
}
#Override
public void onCancelled(DatabaseError databaseError) {
Log.d(TAG1, "failed to read value: " + databaseError.toException());
}
});
How can get my code to filter out every animal that does not have their ID in the user node?
The reason I want to make the user get access with an UID stored in the database is because later on I want to make it so that multiple users can get access to the same animal.

To achieve this, you need to query your database twice. Please use the following code:
FirebaseUser firebaseUser = firebaseAuth.getCurrentUser();
String uid = firebaseUser.getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = usersRef.child("users").child(uid);
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String aid = ds.getKey();
DatabaseReference animalRef = rootRef.child("animals").child(aid);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dSnapshot) {
int age = dSnapshot.child("age").getValue(Integer.class);
String name = dSnapshot.child("name").getValue(String.class);
String url = dSnapshot.child("url").getValue(String.class);
Log.d("TAG", age + " / " + name + " / " + url);
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
animalRef.addListenerForSingleValueEvent(valueEventListener);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
uidRef.addListenerForSingleValueEvent(eventListener);
In which uid is the id of the logged-in user and aid is the id of the animal. Your output will be:
11 / dog1 / http...
12 / dog2 / http...

Hope you find this helpfull.!
Get Object in Your Model Class and Store that Object in List for Further user.!
You can get specific object as well simple using
mdatabaseRef.child("animals").orderByChild().equalTo("value")
and also you can add check on key by orderByKey()
private FirebaseAuth mAuth;
private FirebaseDatabase mdatabase;
private DatabaseReference mdatabaseRef;
mAuth = FirebaseAuth.getInstance();
mdatabase = FirebaseDatabase.getInstance();
mdatabaseRef = mdatabase.getReference();
ArrayList<User> allUserList = new ArrayList<>();
Array<Animal> allAnimalList=new ArrayList<>();
mdatabaseRef.child("animals").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot childSnapshot : dataSnapshot.getChildren()) {
String key = childSnapshot.getKey();
Animal animal = childSnapshot.getValue(Animal.class);
allAnimalList.add(animal );
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
mdatabaseRef.child("users").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot childSnapshot : dataSnapshot.getChildren()) {
String key = childSnapshot.getKey();
User user = childSnapshot.getValue(User .class);
allUserList.add(user);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});

I ended up taking Alex Mamo's answer and tweak with a litte bit.
This is the code i'am using:
uid = currentUser.getUid();
mRootRef = FirebaseDatabase.getInstance().getReference();
final DatabaseReference myUserRef = mRootRef.child("users").child(uid);
Log.d(TAG1, uid);
myUserRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
list = new ArrayList<AnimalCard>();
for(DataSnapshot ds : dataSnapshot.getChildren()){
String aid = ds.getKey();
DatabaseReference myAnimalRef = mRootRef.child("animals");
Query query = myAnimalRef.orderByKey().equalTo(aid);
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot ds2 : dataSnapshot.getChildren()){
AnimalCard value = ds2.getValue(AnimalCard.class);
AnimalCard animal = new AnimalCard();
String name = value.getName();
int age = value.getAge();
String url = value.getUrl();
animal.setName(name);
animal.setAge(age);
animal.setUrl(url);
list.add(animal);
}
recyclerViewSetAdapter();
progressDialog.dismiss();
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
The main difference is that i'am using a query to filter out every Animal that does not have the aID that the currentUser have.