使用recyclerview android从firebase中删除

Question

我已经设置了一个 RecyclerViewAdapter，我可以完美地添加帖子，但是在 firebase 中我只定义了一个集合而不是文档，所以 firebase 生成一个随机字符串，我可以获得字符串详细信息，但我不知道如何与 recyclerview 协调，这样当我滑动删除它时，它会获取相关的字符串并将其从 firebase 中删除，目前它只需要创建最新的字符串并将其删除。

firebase database string My app showing the same reference 如您所见，我可以获取字符串值，甚至使用 getter 和 setter 将其存储为字段，但我不知道如何引用它以删除正确的文档。

我的对象在一个活动（活动 1）中创建并在另一个活动（活动 2）中显示。

活动一：

filepath.putFile(imageUri).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
   @Override
   public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {

   filepath.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
   @Override
   public void onSuccess(Uri uri) {
   String imageUrl = uri.toString(); //creates a URL that links to the images


   final Journal journal = new Journal();
   journal.setTitle(title);
                                journal.setDescription(description);
                                journal.setImageUrl(imageUrl);
                                journal.setTimeAdded(new Timestamp(new Date()));
                                journal.setUsername(currentUserName);
                                journal.setUserId(currentUserId);
                                journal.setDocRef(documentId);

                            JournalApi.getInstance().setDocRef(journal.getDocRef());
                            collectionReference.document(documentId).set(journal).addOnSuccessListener(new OnSuccessListener<Void>() {


@Override
 public void onSuccess(Void aVoid) {
postJournalProgressBar.setVisibility(View.INVISIBLE);
Intent intent = new Intent(PostJournalActivity.this, JournalListActivity.class);
                                        startActivity(intent);
                                        finish();
                                    }
                                }).addOnFailureListener(new OnFailureListener() {
                                    @Override
                                    public void onFailure(@NonNull Exception e) {
                                        Toast.makeText(PostJournalActivity.this, "Something went wrong", Toast.LENGTH_SHORT).show();
                                        Log.d(TAG, "onFailure: when saving the journal" + e.getMessage());
                                    }
                                });
                                //save a journal instance
                            }
                        }).addOnFailureListener(new OnFailureListener() {
                            @Override
                            public void onFailure(@NonNull Exception e) {

}
});
}
});
}}

活动二：

@Override
    protected void onStart() {
        super.onStart();
        collectionReference.whereEqualTo("userId", JournalApi
                .getInstance()
                .getUserId())
                .get()
                .addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
                    @Override
                    public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
                        if (!queryDocumentSnapshots.isEmpty()) {
                            for (QueryDocumentSnapshot journals : queryDocumentSnapshots) {
                                /**/
                                journal = journals.toObject(Journal.class);
                                journalList.add(journal);

                                docList.add(journal.getDocRef());


                            }
                            journalRecyclerViewAdapter = new RecyclerViewAdapter(JournalListActivity.this, journalList);
                            recyclerView.setAdapter(journalRecyclerViewAdapter);
                            journalRecyclerViewAdapter.notifyDataSetChanged();
                        } else {
                            noJournalEntry.setVisibility(View.VISIBLE);
                        }
                    }
                })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                }
            });

}



//Swipe To Delete
    ItemTouchHelper.SimpleCallback swipeToDelete = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.RIGHT) {
        @Override
        public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
            return false;
        }
        @Override
        public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
            //removes the data from the recyclerview and adds corrects the screen accordingly
            journalList.remove(viewHolder.getAdapterPosition());
        journalRecyclerViewAdapter.notifyDataSetChanged();
        journalRecyclerViewAdapter.deleteItem(viewHolder.getAdapterPosition());

        deleteItem();
    }
};

private void deleteItem() {

    collectionReference.document(testDocumentId).set(journal);


    db.collection("Journal")
            .document(testDocumentId)
            .delete().addOnSuccessListener(new OnSuccessListener<Void>() {
        @Override
        public void onSuccess(Void aVoid) {
            Toast.makeText(JournalListActivity.this, "Deleted?", Toast.LENGTH_SHORT).show();
        }
    }).addOnFailureListener(new OnFailureListener() {
        @Override
        public void onFailure(@NonNull Exception e) {
            Toast.makeText(JournalListActivity.this, "NOPE", Toast.LENGTH_SHORT).show();
        }
    });

我可以引用 recyclerview 适配器，以便从手机中删除视图并正确更新，但是一旦我刷新它就会回来，因为我无法从数据库中删除

Answer 1

据我所知，当您在查询的 onSuccess 处理程序中从 Firestore 获取文档时，您会做两件事：

1. 您将文档的数据添加到journalList 作为Journal
2. 您将文档的引用添加到docList

这意味着当您从journalList 中删除Journal 时，您还可以从docList 中获取/删除引用并从Firestore 中删除文档。

代码应如下所示：

public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
    int position = viewHolder.getAdapterPosition();
    collectionReference.document(docList.get(position)).delete();
    docList.remove(position).delete();
    journalList.remove(position);
    journalRecyclerViewAdapter.notifyDataSetChanged();
    journalRecyclerViewAdapter.deleteItem(viewHolder.getAdapterPosition());
}