java从云Firestore获取地图数据

Question

我想从cloud Firestore获取地图数据，这是我在swift中访问同一数据库所需的java代码。我附上了java代码和数据库结构图以供参考

FirebaseFirestore db = FirebaseFirestore.getInstance();
    DocumentReference mDocRef = db.collection("hmdhAcademy").document("notifications");

    mDocRef.get().addOnCompleteListener(task -> {

        if ( task.isSuccessful() ) {

            DocumentSnapshot documentSnapshot = task.getResult();

            if ( documentSnapshot != null && documentSnapshot.exists() ){

                notificationList = (ArrayList) documentSnapshot.get("userNotifications");
                adapter = new NotificationAdapter(this,notificationList);
                mRecyclerView.setAdapter(adapter);
                alertDialog.dismiss();
            }
        }
        else {

            Toast.makeText(NotificationActivity.this,"Check Internet Connection",Toast.LENGTH_SHORT).show();
            alertDialog.dismiss();
        }

    });

if ( list.get(i) instanceof  HashMap ){

        final Intent intent = new Intent(mContext,NotificationDetail.class);

        String title = (String)((HashMap)list.get((list.size()-1)-i)).get("title");
        String body = (String)((HashMap)list.get((list.size()-1)-i)).get("body");
        String image = (String)((HashMap)list.get((list.size()-1)-i)).get("notiImage");
        String detail = (String)((HashMap)list.get((list.size()-1)-i)).get("detail");
}

我需要相同的标题，身体，而不是图像和细节

请帮助我，我正在寻找答案，但失败了

Answer 1

请尝试以下代码：

docRef.getDocument { (document, error) in
if let document = document, document.exists {
    print(document.data()!)
    let userNotifications = document.data()["userNotifications"] as? [[String:Any]]
    for notificaton in userNotifications  {
        let body = notificaton["body"] as? String ?? ""
        let title = notificaton["title"] as? String ?? ""
        print(body, title)

    }

} else {
    print("Document does not exist")
}
}

或者试试这样：

1. 创建一个结构

   struct usernotifcatons {
   
   var body: String = ""
   var detail: String = ""
   var notiImage: String = ""
   var title: String = ""
   
   
   init(notificationData: [String:Any]) {
   
   let body = notificationData["body"] as? String ?? ""
   self.body = body
   
   let detail = notificationData["detail"] as? String ?? ""
   self.detail = detail
   
   let notiImage = notificationData["notiImage"] as? String ?? ""
   self.notiImage = notiImage
   
   let title = notificationData["title"] as? String ?? ""
   self.title = title
    }
   
   }
   

2. 在ViewController中创建一个变量：

   var allNotifications: [usernotifcatons] = [usernotifcatons]()
   

3. 将所有数据映射到firestore代码的一行中

   docRef.getDocument { (document, error) in
   if let document = document, document.exists {
   print(document.data()!)
   let userNotifications = document.data()?["userNotifications"] as? [[String:Any]]
   for data in userNotifications! {
               self.allNotifications.append(usernotifications(notificationData: data))
           }
   print(self.allNotifications)
   
     } else {
   print("Document does not exist")
    }
   }