How to associate data displayed in RecyclerView with documents in Firebase

Question

I have the following situation, namely:

I get documents from a database and convert them to objects:

Code:

private void getProductsFromDatabaseBreakfast() {

        breakfastProducts.clear();

        firebaseFirestore.collection("Users").document(currentUserUID)
                .collection("Types of Meals").document("Breakfast")
                .collection("Date of Breakfast").document(date)
                .collection("List of Products")
                .get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
            @Override
            public void onComplete(@NonNull Task<QuerySnapshot> task) {

                if(task.isSuccessful()) {

                    for(DocumentSnapshot documentSnapshot: task.getResult().getDocuments()) {

                        Log.i("id", documentSnapshot.getId());

                        breakfastProducts.add(documentSnapshot.toObject(Product.class));
                    }
                }

                if(getFragmentRefreshAdapter() != null) {

                    getFragmentRefreshAdapter().onRefresh();
                }
            }
        });
    }

Structure:

Then I display products in RecyclerView:

Going to the merits, I would like the user to be able to change the specifics of the product, and precisely its weight, which will automatically change the other values ​​(calories, protein etc.).

Therefore, after clicking on a given item RecyclerView I go to an activity in which the user can make changes to the product. How can I associate a given product that the user has chosen with the corresponding product in CloudFirestore? That changes would also take place in the document.

I was thinking about incrementing the product ID then I could associate the product with the product position in ReyclerView but I read that it is not good practice or is there any other way?

Answer 1

If the user clicks on an item, then send the name to the other activity and then do a query:

CollectionReference ref = firebaseFirestore.collection("Users").document(currentUserUID)
                .collection("Types of Meals").document("Breakfast")
                .collection("Date of Breakfast").document(date)
                .collection("List of Products");

ref.whereEqualTo("name", name).get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
            @Override
            public void onComplete(@NonNull Task<QuerySnapshot> task) {
                if(task.isSuccessful()) {
                    for(DocumentSnapshot documentSnapshot: task.getResult().getDocuments()) {
                      Map<String, Object> data = new HashMap<>();
                        data.put("weight", 200);
                        ref.document(documentSnapshot.getId()).set(data, SetOptions.merge());
                    }
                }
            }
        });

Use the query whereEqualTo to query that will return all names with the name Chicken breast meat , then after task is successful update the document with the data that the user entered.

https://firebase.google.com/docs/firestore/query-data/queries

https://firebase.google.com/docs/firestore/manage-data/add-data#set_a_document