Android Studio-如何从Firestore的子集合中获取文档？

Question

I would like to get documents in a sub-collection where the date=DATE and title=TITLE in a document. I'm using date and title as primary keys so that I can display information from the documents from sub-collection "bulletin". How would I do that in Android Studio?

Or would it be better to use a different structure?

Thanks!

Image - Firestore Structure

Answer 1

To solve this, please use the following lines of code:

FirebaseFirestore rootRef = FirebaseFirestore.getInstance();
CollectionReference bulletinRef = rootRef.collection("bulletin");
bulletinRef.whereEqualTo("date", date).whereEqualTo("title", title).get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
    @Override
    public void onComplete(@NonNull Task<QuerySnapshot> task) {
        if (task.isSuccessful()) {
            for (QueryDocumentSnapshot document : task.getResult()) {
                Log.d(TAG, document.getString("title"));
            }
        } else {
            Log.d(TAG, "Error getting documents: ", task.getException());
        }
    }
});

The result in your logcat will be, all titles from all documents within your bulletin collection.