Ios 筛选唯一值以在邮件收件箱中显示唯一用户名
我想过滤receiverID,这样我将只获得唯一的receiverID。下面是我的代码:Ios 筛选唯一值以在邮件收件箱中显示唯一用户名,ios,swift,firebase,google-cloud-firestore,Ios,Swift,Firebase,Google Cloud Firestore,我想过滤receiverID,这样我将只获得唯一的receiverID。下面是我的代码: func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell{ let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellIdentifier
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellIdentifier, for: indexPath) as! InboxCollectionViewCell
cell.inboxMessage.text = chats[indexPath.row].receiverID
return cell
}
func loadPosts() {
let senderIDNumber = Auth.auth().currentUser?.uid
let chatsRef = db.collection("chats")
chatsRef.whereField("senderID", isEqualTo: senderIDNumber!)
.addSnapshotListener { querySnapshot, error in
guard let documents = querySnapshot?.documents else {
print("Error fetching documents: \(error!)")
return
}
for document in documents {
let messageText = document.data()["message"] as? String
let senderIDNumber = document.data()["senderID"] as? String
let receiverIDNumber = document.data()["receiverID"] as? String
let timestamp = document.data()["timestamp"] as? String
let conversationsCounter = document.data()["conversationsCounter"] as? Int
let chat = Chat(messageTextString: messageText!, senderIDNumber: senderIDNumber!, receiverIDNumber: receiverIDNumber!, timeStampString: timestamp!, conversationsCounterInt: conversationsCounter!)
self.chats.append(chat)
print(self.chats)
self.collectionView.reloadData()
}
}
}
有没有关于如何过滤以便我的inboxMessage显示唯一用户的想法?我正在使用Firebase/Firestore作为我的数据库。听起来你好像在试图按收件人对结果进行分组。Firestore的查询API中没有这样的GROUPBY子句。您必须自己循环所有消息,并将它们分组到客户端
chatsRef.whereField("senderID", isEqualTo: senderIDNumber!)
.order(by: "receiverID")
.addSnapshotListener { querySnapshot, error in
...
let lastReceiverID = "";
for document in documents {
...
let receiverIDNumber = document.data()["receiverID"] as? String
if receiverIDNumber != lastReceiverId {
// TODO: do something with receiverIDNumber
}
lastReceiverId = receiverIDNumber
}
事实上,您的数据模型目前看起来像是在所有用户之间有一个单一的、很长的聊天消息列表,这感觉像是从用于聊天的关系数据模型的非常直接的转换
在NoSQL数据库中,您通常希望数据建模更接近应用程序实际需要的数据。例如,您似乎试图显示给定发件人的所有邮件。在这种情况下,考虑将这些消息存储在单独的集合中。例如,如果您已经有一个顶级/users
集合,那么您可以将他们在子集合中发送的消息发送到下面:/users/$uid/sent
有关数据建模注意事项的更多信息,请参阅和Todd关于Cloud Firestore(和)的视频系列