How to Get Child of Child Value from Firebase in Android

How to get child of child value from firebase in android?

To access a value in your database, you create a DatabaseReference for that location. Here are three references to locations in your database:

DatabaseReference zonesRef = FirebaseDatabase.getInstance().getReference("ZONES");
DatabaseReference zone1Ref = zonesRef.child("ZONE_1");
DatabaseReference zone1NameRef = zone1Ref.child("ZNAME");

In this snippet:

• zonesRef points to /ZONES
• zone1Ref points to /ZONES/ZONE_1
• zone1NameRef points to /ZONES/ZONE_1/ZNAME

See the Firebase documentation on getting a database reference for more information.

You can attach a listener to each of the references, to get the value at that location. For example, to get the value of the /ZONES/ZONE_1/ZNAME:

zone1NameRef.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        Log.i(TAG, dataSnapshot.getValue(String.class));
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        Log.w(TAG, "onCancelled", databaseError.toException());
    }
});

For more on this type of read operation, see the Firebase documentation on reading values.

If you instead listen on /ZONES/ZONE_1, you will get a DataSnapshot of the entire node with all its properties. You then use DataSnapshot.child() to get the ZNAME from it:

zone1Ref.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        Log.i(TAG, dataSnapshot.child("ZNAME").getValue(String.class));
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        Log.w(TAG, "onCancelled", databaseError.toException());
    }
});

One more level up, you can listen on /ZONES, which will get you a snapshot with all the zones. Since this handles multiple children, you will need to loop through them with DataSnapshot.getChildren():

zonesRef.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot zoneSnapshot: dataSnapshot.getChildren()) {
            Log.i(TAG, zoneSnapshot.child("ZNAME").getValue(String.class));
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        Log.w(TAG, "onCancelled", databaseError.toException());
    }
});

For more on this, see the Firebase documentation on listening for lists of data.

Finally, you might want to query to find a specific zone, for example to find the zone with "ZCODE": "ECOR":

Query zonesQuery = zonesRef.orderByChild("ZCODE").equalTo("ECOR");
zonesQuery.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot zoneSnapshot: dataSnapshot.getChildren()) {
            Log.i(TAG, zoneSnapshot.child("ZNAME").getValue(String.class));
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        Log.w(TAG, "onCancelled", databaseError.toException());
    }
});

To learn more about this, read the Firebase documentation on sorting and filtering data.

How to get child of child value from firebase whose parent value is unknown in java

After reading the various answers on this topic linked above by Mr. @Frank van Puffelen and spending some times over it, the problem is finally solved now without changing my database structure.
Below is screenshot of the result which I wanted:

Here is my modified and working code :

private void retrieveData() {

    final String shift = kvName.getText().toString();
    final String employeeCode = empCode.getText().toString();

    final DatabaseReference aparRef = dbRef.child("Apar").child(shift);

    aparRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

            list = new ArrayList<>();

            if (dataSnapshot.exists()) {

                for (DataSnapshot dataS1 : dataSnapshot.getChildren()) {

                    if (dataS1.hasChild(employeeCode)) {

                        AparData aparData = dataS1.child(employeeCode).getValue(AparData.class);
                        list.add(aparData);

                        rvAPAR.setHasFixedSize(true);
                        rvAPAR.setLayoutManager(new LinearLayoutManager(Apar.this));
                        rvAPAR.setItemAnimator(new DefaultItemAnimator());
                        aparAdapter = new AparAdapter(Apar.this, list);
                        rvAPAR.setAdapter(aparAdapter);

                    } else {
                        Toast.makeText(Apar.this, "No Data Found!!", Toast.LENGTH_SHORT).show();
                    }

                }
            } else {
                Toast.makeText(Apar.this, "Not Data Found!!", Toast.LENGTH_SHORT).show();
            }
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });

}

How to get the child from firebase in android studio?

If you only need the value of the "Egg" property, create a reference that points to the exact property and get it's value as in following lines of code:

String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference eggRef = rootRef.child("Users").child("Customer").child(uid).child("Order").child("Egg");
    productsRef.get().addOnCompleteListener(new OnCompleteListener<DataSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DataSnapshot> task) {
        if (task.isSuccessful()) {
            String value = task.getResult().getValue(String.class);
            Log.d("TAG", value);
        } else {
            Log.d("TAG", task.getException().getMessage()); //Don't ignore potential errors!
        }
    }
});

The result in the logcat will be:

10

If you want a user to have multiple orders, you should consider using a schema that looks like this:

Firebase-root
  |
  --- Users
       |
       --- $uid
            |
            --- orders
                 |
                 --- $pushedId
                 |     |
                 |     --- //Order details
                 |
                 --- $pushedId
                       |
                       --- //Order details

So you need to differentiate each order by calling push() method.

Edit:

According to your last comment:

I wanted to know the code for getting multiple children inside the order (Suppose Egg:10 Onion:5 and so on ) so how do I get that?

Here is your code:

String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference orderRef = rootRef.child("Users").child("Customer").child(uid).child("Order");
orderRef.get().addOnCompleteListener(new OnCompleteListener<DataSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DataSnapshot> task) {
        if (task.isSuccessful()) {
            for (DataSnapshot ds : task.getResult().getChildren()) {
                String key = ds.getKey();
                String value = ds.getValue(String.class);
                Log.d("TAG", key + ":" + value);
            }
        } else {
            Log.d("TAG", task.getException().getMessage()); //Don't ignore potential errors!
        }
    }
});

The result in the logcat will be:

Egg:10
Onion:5

The result in the

Retrieve child node value from firebase with push keys as parent

You'll have to loop over the child nodes of the snapshot you get:

RootRef.child("FirstReply").child(Enquiry_MessageID).addValueEventListener(new ValueEventListener() {
  @Override
  public void onDataChange(@NonNull DataSnapshot snapshot) {
    for (DataSnapshot child: snapshot.getChildren()) { // loop over the child nodes
      String returnSellerID = child.child("sellerId").getValue().toString();
      if(returnSellerID.equals(current_user_Id)) { // use equals to compare strings
        //my remaining code
      }
    }
  }

  @Override
  public void onCancelled(@NonNull DatabaseError error) {
    throw error.toException(); // never ignore errors
  }
});

Android - Firebase - Getting Child of Child Data

According to the data model and looking at this statement

jSettingsDatabase = FirebaseDatabase.getInstance().getReference().child("Resident").child(settingsUserID);

there's no node User underneath /Resident/userId. The query needs to start at the database's root which, I assume, is User.

In order to get London, Washington, etc. you need to adapt the code to:

jSettingsDatabase = FirebaseDatabase.getInstance().getReference().child("Users");
...
jSettingsDatabase.addValueEventListener(new ValueEventListener() {
   @Override
   public void onDataChange(DataSnapshot dataSnapshot) {
      for(DataSnapshot node : dataSnapshot.getChildren()) {
         // you will get all cities
         String stgUserHomeName = node.getKey();
         if(!"Washington".equals(stgUserHomeName)) // or whatever city you need
            continue;
         // add some more conditional logic to cope with the distinct subtrees that don't have the same properties
         // London's Resident has more properties than Washington --> exception is thrown then
         // to get the resident's data
         node.child("Resident").child(userId).child("address")...
         node.child("Resident").child(userId).child("image")...
         // or
         node.child("Resident").child(userId).getValue(Resident.class);
         ...
      }
      ....
   }
});

There's no user ID in your tree that is needed for this query. But it might be necessary depending on the DB's access rules. Obviously the other queries need to be adapted as well. The city names are also not values but a key (must be unique) so what is important to call DataSnapshot.getKey() method.

In your case the whole database from the User downwards will be fetched and on the client all cities that are not needed will be thrown away. That's a waste of resources.

How to retrieve child value from firebase?

After getting the whole list from Firebase iterate them one by one to add them in the list, after the loop set them in the adapter of RecyclerView, and set the adapter to your desired RecyclerView

 @Override
 public void onDataChange(DataSnapshot dataSnapshot) {
                // This method is called once with the initial value and again
                // whenever data at this location is updated.
                list = new ArrayList<CallLogList>();
                for(DataSnapshot dataSnapshot1 :dataSnapshot.getChildren()){

                   CallLogList logList = snapshot.getValue(CallLogList.class);
                   list.add(logList);

                }

                yourAdapter = YourAdapter(list);
                yourRecyclerView.setAdapter(yourAdapter);

            }

For more info, here is a full example

Note: If you are using LiveData or Paging then setting adapters is different, Let me know if you need more example

how to get all child with specific value from Firebase android kotlin?

You'll need to navigate over the dataSnapshot in your onDataChange to get to the correct child nodes.

To navigate a DataSnapshot object you have two main approaches:

1. You already know the key of the child you want to access, in which case you use the child() method to access that specific child node. For example, you could read the marked child in the JSON with dataSnapshot.child("Turcia/Adana/Çukurova University/Faculty of Business").children.map, similarly to what you already tried on the reference.
2. You don't know the key of the child nodes, in which case you loop over the getChildren() property of the snapshot. For an example of the latter, see the Firebase documentation on listening for value events on a list of children.

I think you're looking for the second approach here, but in any case you're dealing with DataSnapshots, there are the ways to get at the data in there.

---

Related Topics