CODEWITHSUNDEEP
javaandroidfirebasegoogle-cloud-firestore
s_o_m_m_y_e_e
s_o_m_m_y_e_e

Reputation: 406

How to get firestore data from a loop and send to recyclerview adaptor

I am loading data from firestore into recycler view android. It is a kind of e-commerce cart system in which the items' Uids are stored.

I have my ArrayList of uids(I've already received it from firestore) and now with it, I need to get DocumentSnapshots of the items by looping the uids Arraylist and adding it to a documentSnapshots Arraylist.
I have tried the following:

ArrayList<DocumentSnapshot> documentSnapshots = new ArrayList<>();
                    
      //getting the document snapshot out of the uids
      for (int i = 0 ; i < uids.size() ; i++){
                        
                 db.collection("items").document(uids.get(i)).get()
                   .addOnCompleteListener(task1 -> {

                                    documentSnapshots.add(task1.getResult());
                                    
                                });
                    }

Then, after getting this data, I send this arraylist to the adaptor as follows:

//sending data to adaptor
adaptorCart = new AdaptorCart(Cart.this , modelCart , db , documentSnapshots);

But I always get the DocumentSnapshots Arraylist empty as because of the asynchronous behaviour of the onCompletelistener so how can I achieve what I want as always in this type of behaviour, I would get an empty list. Also, I tried using callback but couldn't get around the problem.

Any help would be so much appreciated!

Upvotes: 0

Views: 143

Answers (1)

Whitebird
Whitebird

Reputation: 238

You can do like this

     ArrayList<DocumentSnapshot> documentSnapshots = new ArrayList<>();
                
  //getting the document snapshot out of the uids
  int count = uids.size();
  for (int i = 0 ; i < uids.size() ; i++){
                    
             db.collection("items").document(uids.get(i)).get()
               .addOnCompleteListener(task1 -> {

                                documentSnapshots.add(task1.getResult());
                                if(documentSnapshots.size() == count){
                                  adaptorCart = new AdaptorCart(Cart.this , modelCart , db , documentSnapshots);
                                }
                                
                            });
                }

Upvotes: 2

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