How to add new child in Firebase database Android

Question

I\'m trying to add a new child using the DatabaseReference in my Firebase Android app. I\'m doing:

DatabaseReference mDatabase = F         


        

Answer 1

You'll need to call push() to generate a unique key for the new data:

DatabaseReference mDatabase = FirebaseDatabase.getInstance().getReference() 
mDatabase.push().setValue(1);

This will append the new value at the end of the list.

By combining the push() and child() methods, you can create multiple lists of children in the database:

mDatabase.child("numbers").push().setValue(1);
mDatabase.child("numbers").push().setValue(53);
mDatabase.child("numbers").push().setValue(42);

mDatabase.child("letters").push().setValue("a");
mDatabase.child("letters").push().setValue("z");
mDatabase.child("letters").push().setValue("c");

See the section append to a list of data in the Firebase documentation.

Answer 2

Another post mentioned to check your gradle app file to ensure you have the latest version of the Firebase as follows:

compile 'com.google.firebase:firebase-core:10.0.1'
compile 'com.google.firebase:firebase-database:10.0.1'

I think this should fix many issues that could arise from using older versions.

I hope this helps.

Answer 3

You cannot add anything to the database if you're not authorized. You can do one of the following:

Either set this to your rules tab in firebase console:

{
"rules": {
".read": true,
".write": true
}
}

Or you must create an authentication first (try with email/pass) and create user with

createUserWithEmailAndPassword(email, password)

and then sign in with:

signInWithEmailAndPassword(email, password)

and you need to enable sign-in with email/pass in your console as well.

And then you can write data to your database.

Answer 4

Check this sample, it may help you out.

     public class FirebaseUserDetails
    {
    private String mDisplayName;
    public String getmDisplayName() {
        return mDisplayName;
    }
public void setmDisplayName(String mDisplayName) {
    this.mDisplayName = mDisplayName;
}
}

Add your value to firebase database,

FirebaseUserDetails firebaseUserDetails = new FirebaseUserDetails();
firebaseUserDetails.setmDisplayName("arunwin");
DatabaseReference pathReference = FirebaseDatabase.getInstance().getReference().child("contacts");
pathReference.child("arun").setValue(firebaseUserDetails).addOnCompleteListener(new OnCompleteListener<Void>() {
    @Override
    public void onComplete(@NonNull Task<Void> task) {

    }
});

And your result value will be added in your database like the below,

contacts:
    arun:
        mDisplayName:"arunwin"

Answer 5

In my case i am adding new child like this!

NOTE : Here i am adding new child refresh_token to my firebase database

FirebaseDatabase.getInstance().getReference().child("RegistrationModel").child(userId)
                    .addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    Map<String, String> stringStringHashMap =(Map<String, String>) dataSnapshot.getValue();

                    stringStringHashMap.put("refresh_token",refreshedToken);

                    FirebaseDatabase.getInstance().getReference().child("RegistrationModel").child(userId)
                            .setValue(stringStringHashMap);

                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });

Answer 6

Use push() before set value in the firebase. It will create new user every time when you send value in the database.