CODEWITHSUNDEEP
androidfirebasefirebase-realtime-database
lifelonglearner
lifelonglearner

Reputation: 27

Firebase query startAt() doesnt return any value?

In my chat app.i want to receive only recently added messages so i am trying to receive message via query startAt() but the query return no data.

please help me to find out where i making a mistake:

this is my data structure: (My Datastructure image)

-Chats
-TrHRsy8x7WYZjodQrNrzfumw16z2g2dojhGBdie07PXqhl47l8GWN1a2
-LastMessage
-Messages
-MCi-gOmhLUl5MuLtCiI
-MCi-hstmFyAfAczexvI
LT: -11108656
T: 1595278548931
c: 2
m: "hi"
r: "g2dojhGBdie07PXqhl47l8GWN1a2"
s: "TrHRsy8x7WYZjodQrNrzfumw16z2"
-MCi-kukmwJpU3ubswId

  Query ref2 = FirebaseDatabase.getInstance().getReference("Chats/" + uniquechatid()).child("Messages").orderByChild("T").startAt("1595278548931");

        receiveListener = ref2.addChildEventListener(new ChildEventListener() {

            @Override
            public void onChildAdded(@NonNull DataSnapshot snapshot, @Nullable String previousChildName) 
            {
                if (snapshot.getValue() != null) {
                    Chat chat = snapshot.getValue(Chat.class);
                    assert chat != null;
                    Log.e("chat added",chat.getM());
                }
            }
});

i want to receive only messages from those timestamp.i even tried the startAt(value,key) .startAt() doesnt work.if i remove startAt() then data receives perfectly.

my message uploading:

  private void sendMessage(String sender, String receiver, String message) {

        DatabaseReference reference = FirebaseDatabase.getInstance().getReference();

        HashMap<String, Object> hashmap = new HashMap<>();
        hashmap.put("s", sender);
        hashmap.put("r", receiver);
        hashmap.put("m", message);
        hashmap.put("c", 1);
        hashmap.put("T",ServerValue.TIMESTAMP);
        hashmap.put("LT",timenow);

        reference.child("Chats/"+uniquechatid()+"/Messages").push().setValue(hashmap);
       
    }

my database rules:

{
  "rules": {
    ".read": true,
    ".write": true,
     "Chats": {
       "$chatid":{
         "Messages":{
         "$messageid":{
           ".indexOn": "T"  
         }   
         }
       }
    }
  }
  
}

Upvotes: 0

Views: 135

Answers (1)

Rajnish Sharma
Rajnish Sharma

Reputation: 388

There is a child of Messages in the pic. You ref2 should be like

Query ref2 = FirebaseDatabase.getInstance().getReference("Chats/" + uniquechatid()).child("Messages/" +"MCi-hstmFyAfAczexvI").orderByChild("T").startAt("1595278548931");

    receiveListener = ref2.addChildEventListener(new ChildEventListener() {

        @Override
        public void onChildAdded(@NonNull DataSnapshot snapshot, @Nullable String previousChildName) 
        {
            if (snapshot.getValue() != null) {
                Chat chat = snapshot.getValue(Chat.class);
                assert chat != null;
                Log.e("chat added",chat.getM());
            }
        }

});

provide message id or the id you are using to store different messages as the child of Messages.

Upvotes: 1

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