How to Efficiently Select Random Products from a Large Firebase Database in Node?-javaTutorial-php.cn

How to Efficiently Select Random Products from a Large Firebase Database in Node?

Barbara Streisand

Release： 2024-10-29 06:12:31

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How to Efficiently Select Random Products from a Large Firebase Database in Node?

Getting Unique Random Products in Node Firebase

To retrieve a single random product from a node database over 1000 records, consider two approaches: the classic solution and a denormalized approach.

Classic Solution

<br>ListView listView = (ListView) findViewById(R.id.list_view);<br>ArrayAdapter arrayAdapter = new ArrayAdapter<>(context, android.R.layout.simple_list_item_1, randomProductList);<br>listView.setAdapter(arrayAdapter);<br>DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();<br>DatabaseReference productsRef = rootRef.child("products"); //Added call to .child("products")<br>ValueEventListener valueEventListener = new ValueEventListener() {</p>
<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">@Override
public void onDataChange(DataSnapshot dataSnapshot) {
    List<String> productList = new ArrayList<>();
    for(DataSnapshot ds : dataSnapshot.getChildren()) {
        String name = ds.child("name").getValue(String.class);
        productList.add(name);
    }

    int productListSize = productList.size();
    List<String> randomProductList = new ArrayList<>();

    randomProductList.add(new Random().nextInt(productListSize)); //Add the random product to list
    arrayAdapter.notifyDatasetChanged();
}

@Override
public void onCancelled(DatabaseError databaseError) {
    Log.d(TAG, "Error: ", task.getException()); //Don't ignore errors!
}

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This approach loops through all product nodes, adds their names to a list, and randomly selects one.

Firebase-root | --- products | | | --- productIdOne | | | | | --- //details | | | --- productIdTwo | | | --- //details | --- productIds <div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false"> | --- productIdOne: true | --- productIdTwo: true | --- //And so on

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference(); DatabaseReference productIdsRef = rootRef.child("productIds"); ValueEventListener valueEventListener = new ValueEventListener() { <div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">@Override public void onDataChange(DataSnapshot dataSnapshot) { List<String> productIdsList = new ArrayList<>(); for(DataSnapshot ds : dataSnapshot.getChildren()) { String productId = ds.getKey(); productIdsList.add(productId); } int productListSize = productList.size(); List<String> randomProductList = new ArrayList<>(); DatabaseReference productIdRef = rootRef.child("products").child(productIdsList.get(new Random().nextInt(int productListSize)); ValueEventListener eventListener = new ValueEventListener() { @Override public void onDataChange(DataSnapshot dataSnapshot) { String name = dataSnapshot.child("name").getValue(String.class); Log.d("TAG", name); } @Override public void onCancelled(DatabaseError databaseError) { Log.d(TAG, "Error: ", task.getException()); //Don't ignore errors! } }; productIdRef.addListenerForSingleValueEvent(eventListener); } @Override public void onCancelled(DatabaseError databaseError) { Log.d(TAG, "Error: ", task.getException()); //Don't ignore errors! }