Query in Firebase with equalTo method

Question

I want to order by timeStamp the comments inside the comments node, get the last 15 messages starting with KsBazxx0bew6UOfUI5J which is a child of the comments node. I´m trying to get the comments using the following code:

FirebaseRef.orderByChild("timeStamp").startAt(commentID).limitToLast(15).addChildEventListener(likeOrCommentsListener);

unfortunetly I'm not able to get any information, which makes me think that the query is wrong. How can I get the messages using those restrictions?

Can you show the child event listener?. It has 5 callback method and at least the return the value which is passed in startAt(), in method onChildAdded(), if there are no other results. — Umar Hussain
– Umar Hussain, Commented Aug 23, 2017 at 5:00
you can't use startAt on ID , you can use it on value of key under ID — saurabh dixit
– saurabh dixit, Commented Aug 23, 2017 at 5:19

Frank van Puffelen · Accepted Answer · 2017-08-23 06:11:56Z

2

Since you're ordering by timestamp, you need to pass in the value of the timestamp where you want to start the query:

FirebaseRef.orderByChild("timeStamp").startAt(150317519355)...

If there may be multiple items with the same timestamp, you can additionally specify that the query should start at a specific key:

FirebaseRef.orderByChild("timeStamp").startAt(150317519355, "KsBazxx0bew6UOfUI5J")...

answered Aug 23, 2017 at 6:11

Frank van Puffelen

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2 Comments

Andrey Solera Over a year ago

thanks for such a quick response, I only have a little problem, it says that the timeStamp 150317519355 is too large to add it i the startAt(), or am I doing something wrong? Many thanks

Frank van Puffelen Over a year ago

I copied the value from your screenshot (next time post the JSON as text please). I might have made a typo, although I don't see it. If you can store a value as a number, you should be able to query it since startAt() takes a double. If you keep having problems, update your question with the code that reproduces the problem.

Manohar · Accepted Answer · 2017-08-23 05:11:22Z

0

Try this

 DatabaseReference databaseReference = Firebase.getInstance().getReference();
Query lastQuery = databaseReference.child("comments").orderByChild("timeStamp").limitToLast(15);
lastQuery.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
       //use this dataSnapshot
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        //Handle possible errors.
    }
});

edited Aug 23, 2017 at 5:11

answered Aug 23, 2017 at 4:53

Manohar

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