从 Firebase 的 Cloud Firestore 中删除文档是否会删除该文档中的任何子集合？

Question

这是我当前如何删除文档的示例：

let transactionsRef = db.collection(Globals.GroupsPath).document(Group.instance.getAll().id).collection(Globals.GroupTransactions)
let query = transactionsRef.whereField(Globals.TransactionCreator, isEqualTo: Auth.auth().currentUser!.uid)
query.getDocuments { (snapshot, error) in
   guard error == nil else {
      print(error!.localizedDescription)
      callback(error)
      return
   }

   if let snapshot = snapshot {
      let batch = self.db.batch()
      for doc in snapshot.documents {
         batch.deleteDocument(doc.reference)
      }
      batch.commit()
      callback(nil)
   }
   // TODO: Create an error here and return it.
}

但是我注意到，在执行此操作后，Firestore 数据库中的文档变灰了，但我仍然可以单击它并查看该文档中的集合及其数据！

我是否需要在删除父文档之前手动删除子集合中的每一项，还是只需要一段时间才能完成删除？这是怎么回事？

Answer 1

删除文档不会删除子集合。您确实需要手动删除所有子集合，如文档中所述 here。您会看到文档不建议从客户端删除子集合，因为有很多方法可能出错。对于客户端来说是labor-intensive，可能会涉及到读写权限问题等。你会想要使用服务器或无服务器解决方案。因此，例如，这就是删除子集合 server-side 与 Node.js:

的工作方式

function deleteCollection(db, collectionPath, batchSize) {
     var collectionRef = db.collection(collectionPath);
     var query = collectionRef.orderBy('__name__').limit(batchSize);

    return new Promise((resolve, reject) => {
        deleteQueryBatch(db, query, batchSize, resolve, reject);
    });
}

function deleteQueryBatch(db, query, batchSize, resolve, reject) {
query.get()
    .then((snapshot) => {
        // When there are no documents left, we are done
        if (snapshot.size == 0) {
            return 0;
        }

        // Delete documents in a batch
        var batch = db.batch();
        snapshot.docs.forEach((doc) => {
            batch.delete(doc.ref);
        });

        return batch.commit().then(() => {
            return snapshot.size;
        });
    }).then((numDeleted) => {
        if (numDeleted === 0) {
            resolve();
            return;
        }

        // Recurse on the next process tick, to avoid
        // exploding the stack.
        process.nextTick(() => {
            deleteQueryBatch(db, query, batchSize, resolve, reject);
        });
    })
    .catch(reject);
}

从 Firebase 的 Cloud Firestore 中删除文档是否会删除该文档中的任何子集合？

Does deleting a document from Firebase's Cloud Firestore delete any sub collections in that document?

firebase

swift4

ios11

google-cloud-firestore