Firebase Android addListenerForSingleValueEvent sometimes not returning data

Question

When my application starts, I check the current user's details in my Firebase database (I'm storing it's uid for that).

I'm attaching addListenerForSingleValueEvent to user's ref to read it's data.

My problem is that sometimes, it doesn't return any value, neither success nor failure.

Only clearing application's data solves it, but of course forces the user to login again.

I've read some posts at SO, but didn't find any solution.

Here's my piece of code:

DatabaseReference newUser =    
FirebaseDatabase.getInstance().getReference("users/"+uid);
newUser.addListenerForSingleValueEvent(new ValueEventListener()     
    @Override
    public void onDataChange(DataSnapshot snapshot) {}

    @Override
    public void onCancelled(DatabaseError databaseError) {}
});

Solution 1

The recommendation I've seen for this is to call keepSynced(true) on the Query object.

Solution 2

Please try like this. If you can't solver by this, send share me source code for this part. ...

DatabaseReference mDatabase = FirebaseDatabase.getInstance().getReference();
mDatabase.child("users").child(uid).addListenerForSingleValueEvent(new ValueEventListener() {

    @Override
    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
        if (dataSnapshot.exists()){
            final HashMap<String, Object> dataMap = (HashMap<String, Object>) dataSnapshot.getValue();
            for (String key : dataMap.keySet()){
                Object data = dataMap.get(key);
                try{
                    HashMap<String, Object> moneyData = (HashMap<String, Object>) data;
                    Money money = new Money(("", "");
                }catch (ClassCastException cce){
                    try{
                        name = String.valueOf(dataMap.get("username"));
                        email = String.valueOf(dataMap.get("useremail"));
                    }catch (ClassCastException cce2){
                    }
                }
            }                            
        // do something
        }else {
        // when empty data
        }
    }
    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
    }
});

Comments

[Frank van Puffelen]

Quick question: are you using authentication? Are you accessing multiple databases in the same app (or have you previously used the same app to access a different database)?

[Adi]

Yes I'm using authentication. I'm only access one database. BTW, even restarting the device didn't solve it.

[Adi]

That problem has started only after I've start using the new SDK.

[andre]

I can reproduce this problem always in combination with the solution of this Question: stackoverflow.com/questions/31670234/… So if I create a Value listener, which contains a single value listener, the single value listener never returns any data so everything freezes. Any solutions for this @FrankvanPuffelen? Do I do something wrong? Open Source project to reproduce, on PM if you like.

[Alejandro Morán]

I had the same problem today, I temporary fixed it by doing a logout of the current user, even when I deleted it from the database it was still available in the app

[Pnemonic]

I too had this problem. Call the firebase.authWithCustomToken BEFORE firebase.addListenerForSingleValueEvent

[Nikunj Patel]

I have same issue with addListenerForSingleValueEvent, is that first time when application was launch, its call properly but next time when i come back on application, its not call any override method. i tried keepsynced and its work now.

[Nikunj Patel]

but fact is there are issue with New SDK