CODEWITHSUNDEEP
androidfirebasefirebase-realtime-database
Kazaka Nelson
Kazaka Nelson

Reputation: 168

When using runTransaction, I got permission denied

I'm developing chat system, calculating total unread count.

here's my code

        chatroomRef.child(chatInfo.getPartner_firebase_uid())
            .child(mChatId)
            .child("totalUnreadCount")
            .runTransaction(new Transaction.Handler() {
                @Override
                public Transaction.Result doTransaction(MutableData mutableData) {
                    Integer totalUnreadCount = mutableData.getValue(Integer.class);
                    if(totalUnreadCount == null){
                        mutableData.setValue(0);
                    }else{
                        mutableData.setValue(totalUnreadCount + 1);
                    }
                    return Transaction.success(mutableData);
                }

                @Override
                public void onComplete(DatabaseError databaseError, boolean b, DataSnapshot dataSnapshot) {
                    Log.d("result", "postTransaction:onComplete:" + databaseError);
                }
            });

When used this code, I got permission denied. But when I used code below, it worked.

chatroomRef.child(chatInfo.getPartner_firebase_uid())
                        .child(mChatId)
                        .child("totalUnreadCount")
                        .setValue(1);

two codes set data change exactly same course in firebase-db. Though one code gets permission error, the other doesn't. So I think it is a problem with firebase rules. And, I gave 'true' to '.write', but got permission error.

Upvotes: 0

Views: 195

Answers (1)

Frank van Puffelen
Frank van Puffelen

Reputation: 599766

It sounds like you don't have permission to read the value of totalUnreadCount. A transaction writes a new value based on the existing value, so it needs both read and write permission.

Upvotes: 2

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