How to check for an empty document on Firestore?

Question

So I am trying to delete a document on Firebase Firestore which contains no fields. But how can I check whether the document contains no data before I delete it

Answer 1

In order to check if the Document incoming is empty, you can check for the number of keys of the stored object. If there are 0 keys stored, you can then delete the document.

Example code in Typescript:

const doc = await firestore()
            .collection('Collection')
            .doc('incoming')
            .get();

const numberOfKeys = Object.keys(doc.data()).length;

if (numberOfKeys === 0) {
    await firestore()
    .collection('Collection')
    .doc('incoming')
    .delete();

Answer 2

To solve this, you should get the data from the database as a Map:

yourDocumentReference.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DocumentSnapshot> task) {
        if (task.isSuccessful()) {
            DocumentSnapshot document = task.getResult();
            if (document.exists()) {
                Map<String, Object> map = document.getData();
                if (map.size() == 0) {
                    Log.d(TAG, "Document is empty!");
                } else {
                    Log.d(TAG, "Document is not empty!");
                }
            }
        }
    }
});

To check a document only for existens it doesn't mean that is empty. The document can exist (like in your screenshot) but has no properties set. Because every document in a Cloud Firestore database is a Map, you can use size() method to see if is empty or not.