FireStore How can i get Collection in an order (Dess / Accen )

Question

i have a collecntion Which Contain Multiple document and i want to fetch higest index document form it

I want to fetch Lat document of Customer_Info but i dont know it value

and i dont know how to implement orderBy in collections => Document => document_Data

Answer 1

If Bill_ID is same as the document ID, you can use orderBy() and limit(1) to get last document in that collection as shown below:

db.collection("(?)/Business/Customer_Info")
        .orderBy("Bill_ID", Direction.DESCENDING)
        .limit(1)
        .get()
        .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
            @Override
            public void onComplete(@NonNull Task<QuerySnapshot> task) {
                if (task.isSuccessful()) {
                    for (QueryDocumentSnapshot document : task.getResult()) {
                        Log.d(TAG, document.getId() + " => " + document.getData());
                    }
                } else {
                    Log.d(TAG, "Error getting documents: ", task.getException());
                }
            }
        });

However, you must ensure the field must be a number or the order will not be correct as Firestore orders them lexicographically.

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You should avoid using sequential documents IDs and using a timestamp to order documents might be a better idea.

Also checkout:

• Limitations of using sequential IDs in Cloud Firestore .
• Order and limit data with Cloud Firestore