[FIXED] I am unable to getValue() from a child in Firebase

Issue

I'm new to Android and Firebase. I'm trying to get a String from the Firebase and compare it with the given string.

Now, when I use getValue(), it displays "Cannot resolve method 'getValue' in 'DatabaseReference'"

Here is the structure of my database

Here the name after the node "user1" will change, so I am refining the database till user1

Every time a new folder is created by the app, a new node is created within user1 with the same structure

Now, I want to compare each string in node "AmazonLink" with the given string

Here is my code

  DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("Users/user1");


else if(databaseReference.child("AmazonLink").getValue().equals(amazonLink.getText()))

Solution

DatabaseReference#child(String pathString) method, returns an object of type DatabaseReference. As you can see, there is no getValue() method inside this class. However, DataSnapshot class does contain a getValue().

So in order to check the value of a field in the Realtime Database against a particular value, you have to perform a query and attach a lister like this:

DatabaseReference db = FirebaseDatabase.getInstance().getReference();
DatabaseReference userOneRef = db.child("Users/user1");
Query query = userOneRef.orderByChild("AmazonLink").equalTo(amazonLink.getText());
query.get().addOnCompleteListener(new OnCompleteListener<DataSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DataSnapshot> task) {
        if (task.isSuccessful()) {
            for (DataSnapshot ds : task.getResult().getChildren()) {
                String amazonLink = ds.child("AmazonLink").getValue(String.class);
                Log.d("TAG", amazonLink);
            }
        } else {
            Log.d("TAG", task.getException().getMessage()); //Never ignore potential errors!
        }
    }
});

See I have used now DataSnapshot#getValue(Class valueType) which indeed allows me to read the value of the field in a String format.

P.S. The above code will work, only if amazonLink.getText() will return the exact value of the field it exists in the database.

Answered By - Alex Mamo
Answer Checked By - Pedro (JavaFixing Volunteer)