CODEWITHSUNDEEP
javaandroidfirebasefirebase-realtime-database
runningmark
runningmark

Reputation: 760

How to update values in android app using firebase?

Hi Please find the structure of firebase DB?

enter image description here

Now let's say, we want to update fName and lName from -LcKJ14wv-Y46QER1V- 0

How to update them so only these values are updated and no new values are added in the database?

Code we have written

queryToGetData = FirebaseDatabase.getInstance().getReference().child(AppData.STUDENTS)
                    .orderByChild("studentUnique").equalTo(user.getUid()).limitToFirst(1);
            queryToGetData.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {

                    if(!dataSnapshot.exists()){
                        db.push().setValue(ss);
                        Common.alertDialog("Added","Profile Details saved", StudentProfile.this);
                    } else {
                        db.setValue(ss);
                        Common.alertDialog("Oops","Profile Updated", StudentProfile.this);
                    }
                }
                @Override
                public void onCancelled(DatabaseError databaseError) {
                    Common.alertDialog("Oops","Something went wrong!", StudentProfile.this);
                }
            });

What this piece of code is doing?

when running update for the first time(the whole collection is empty)

enter image description here

*when running update for the second time(same user)

enter image description here

when running update for the third time(same user)

enter image description here

Upvotes: 1

Views: 956

Answers (3)

Alex Mamo
Alex Mamo

Reputation: 138824

I agree with what @elbert rivas said regarding the use of the uid to identify your users rather than a pushed id. In that case, to update a user object, you don't need a query. However, if can't change your database structure, you can still update a user object like in the following lines of code:

queryToGetData = FirebaseDatabase.getInstance().getReference().child(AppData.STUDENTS)
                .orderByChild("studentUnique").equalTo(user.getUid());
ValueEventListener valueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            Map<String, Object> map = new HashMap<>();
            map.put("fName", "newFirstName");
            map.put("lName", "newLastName");
            ds.getRef().updateChildren(map);
        }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
        Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
    }
};
queryToGetData.addListenerForSingleValueEvent(valueEventListener);

See, I have removed the .limitToFirst(1) because the uid of a user are unique. So even if we remove that method call, you'll still get a single result.

Upvotes: 0

elbert rivas
elbert rivas

Reputation: 1464

First I would suggest to restructure your db like this for much simpler query. 

students
    QslkALDJFLDFLFk(this is the student unique key or the uid)
        emailAddress:
        fName:

Then use updateChildren() to update specific fields. 

Student student = new Student("firstName", "lastName");
Map<String, Object> values = student.toMap();

queryToGetData = FirebaseDatabase.getInstance().getReference()
    .child(AppData.STUDENTS).child(user.getUid())
    .updateChildren(values);

You can read the documentation here

Upvotes: 1

Sandeep Malik
Sandeep Malik

Reputation: 1976

i am doing this way ;- 

DatabaseReference receiverUserRef = FirebaseDatabase.getInstance().getReference(chatListTableName)
                .child(userId)
                .child(firebaseUser.getUid());

        receiverUserRef.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                if (dataSnapshot.exists()) {
                    receiverUserRef.child("time").setValue(String.valueOf(System.currentTimeMillis()));
                } else {
                    receiverUserRef.child("id").setValue(firebaseUser.getUid());
                    receiverUserRef.child("isGroup").setValue("false");
                    receiverUserRef.child("time").setValue(String.valueOf(System.currentTimeMillis()));
                }
            }
            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });

Upvotes: 0

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