如何提取id中特定部分等于某个字符串的Firebase中的所有子代 [英] how to extract all child in firebase with certain part of the id iqual to some string

问题描述

具有此Firebase结构我如何仅检索与该孩子聊天的孩子键几乎具有当前用户ID. 聊天的孩子ID如下 11-126

having this firebase structure how do i retrive only the childs of chats that child key have almost the current user id. the chats child id are like this 11-126

所以说mi用户id我们11.我想用-的任何一边都具有11的所有数据检索所有子项.如果有一个89-11 o 253-11 o 11-254的孩子，我想取回所有这些孩子. 现在，我正在检索所有孩子，并查看密钥是否包含我对此代码感兴趣的ID.

so let say mi user id us 11. i want to retrive all child with all it data that have 11 in any side of - . if there is a child with 89-11 o 253-11 o 11-254 i want to retrive all of those childrens. now i'm retriving all child and watching if key contains the id im interested whit this code.

chatsRef.observe(.childAdded, with: { [weak self] snapshot in
        if snapshot.key.contains(String(requestManager.instance.user.id!)){
            if let data = snapshot.value as? [String: Any]{
                let id = data["id"] as! String
                let name = data["name"] as! String
                let message = data["body"] as? String
                let senderId = data["senderId"] as! String
                let url = self?.rootRef.child("user").child(senderId).value(forKey: "url") as? String

            }
        }
    })

转换为字典后，出现错误.

afer the conversion to Dictionary I got an error.

线程1:致命错误:展开包装时意外发现nil 可选值.

Thread 1: Fatal error: Unexpectedly found nil while unwrapping an optional value.

数据值是这个.

似乎是data ["0"].value可以正常工作，但事实并非如此.知道如何提取添加的子项的所有值

seem to be that data["0"].value wourl work but it does not. Any idea how to extract all the values of the child added

推荐答案

听起来您想检索用户11的所有聊天记录，这意味着senderId或recipientId是11. Firebase实时数据库无法支持这种类型的OR查询，该数据库仅支持对单个属性的查询.

It sounds like you want to retrieve all chats for user 11, which means that either senderId or recipientId is 11. This type of OR query is not possible with the Firebase Realtime Database, which only supports queries on a single property.

相反，向您的JSON添加一个数据结构，该数据结构包含每个用户ID的聊天室ID.所以:

Instead, add a data structure to your JSON that holds the chat room IDs for each user ID. So:

"userChats": {
  "11": {
    "11-126": true
  } 
  "126": {
    "11-126": true
  }
}

使用此附加数据结构，您可以轻松地在/userChats/$uid下为用户查找聊天室，然后为其加载单个聊天室.

With this additional data structure you can easily look up the chat rooms for a user under /userChats/$uid and then load the individual chat rooms for them.

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