FIRESTORE - Insert a subCollection inside a document

Dan Jhay :

I have a collection named Reports in my Firestore database, I've already done adding documents inside it. But my problem now is I want to add a Document with a SubCollection inside Reports, any Idea?

public CollectionReference Ref = firestore.collection("Reports");
Reports reports = new Reports(date, cash, total, discount, quantity, sum, employee);
Ref.add(reports);

Alex Mamo :

Reports cannot be a document, it can only be a collection. So assuming you have a database structure that look like this:

Firestore-root
    |
    --- Reports (collection)
          |
          --- reportId (document)
                |
                --- // report details

To add a new collection under the reportId document which in term contains other documents, please use the following line of code:

FirebaseFirestore rootRef = FirebaseFirestore.getInstance();
CollectionReference ref = rootRef
    .collection("Reports").document(reportId)
    .collection("NewCollection").document(newCollectionId);
ref.add(reports);

And your new sturcture will look like this:

Firestore-root
    |
    --- Reports (collection)
          |
          --- reportId (document)
                |
                --- // report details
                |
                --- NewCollection (collection)
                       |
                       --- newCollectionId (document)
                              |
                              ---//  newCollectionId details