Conditional delete from Adapter

Question

Sorry in advance if my question sounds silly. I am a newby. In my app I have an adapter which shows the documents queried from Firebase Firestore.
At the moment there is a OnSwipe listener which can delete documents. I want to set it the way that the only documents which were recorded by the certain user can be deleted. Meaning: user can only delete documents writen by him and cannot delete documents written by others. Please advise how to do this?

At the moment the code looks like this:

new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | 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) {

                adapter.deleteItem(viewHolder.getAdapterPosition());

            }
        }).attachToRecyclerView(recyclerView);

Answer 1

You need to implement security rules to restrict the delete operation to the author of the document. In this document[1], it mentions how to set rules for write, which also contains create, update, and delete rules [2] . So you can set a rule like:

service cloud.firestore {
    match /databases/{database}/documents {
        match /{document=**} {
            allow read; 
            allow delete: if request.auth.uid == resource.data.userid;
        }
    }
}

As mentioned above, it would be clearer if you could provide the contents of deleteitem(), and the document structure.

[1]https://firebase.google.com/docs/firestore/security/rules-query [2] https://firebase.google.com/docs/firestore/security/rules-structure#granular_operations

Answer 2

Thank you all for your help. I did modify my delete method and it worked: Thank you for your hints and help

 public void deleteItem(int position, String userID) {
    String docUserID = getSnapshots().getSnapshot(position).getString("userID");
    Log.i("deleteItem", "docUserID: " + docUserID + " userID: " + userID);
    if (docUserID != null) {
        if (docUserID.equals(userID)) {
            getSnapshots().getSnapshot(position).getReference().delete();
            Log.i("deleteItem", " if worked... ");

        } else {
            Log.i("deleteItem", " if did not work");
        }
    }

}