ios - 通过观察Firebase中的数据库引用无法获取顶级节点的值

我正在尝试以Swift语言从Firebase数据库（在此示例中为[branch1，branch2]）获取分支列表，
当我观察到顶部节点（“分支”）时，它什么也不返回，甚至没有调用第一个打印函数，但是如果观察到像branch1这样的分支之一，它就可以正常工作。
现在如何检索分支列表（[branch1，branch2]）

    let ref = FIRDatabase.database().reference()

    ref.child("branches").observe(.value, with: { snapshot in

        print("+++++++++++++++++ ")

        print("++++++++++++\(snapshot.hasChildren())")
        for child in snapshot.children{

            let branch = child as! FIRDataSnapshot
            let branchName = branch.key as! String
            print("\(branchName)")
       }

   }

enter image description here

{  "Users" : {
"6dICrkbVVJWzVZ00Vq4y9Fm2Qcg2" : {
  "branches" : {
    "branch1" : true
  },
  "isAdmin" : true
},
"M0C1XUyboPg5zbgQi24nh3SlJri1" : {
  "branches" : {
    "branch2" : true
  }
}  },"branches" : {
"branch1" : {
  "address" : "NDG",
  "campaigns" : {
    "valentine's day" : true
  },
  "manager" : "y",
  "rate" : {
    "average" : 0,
    "bad" : 0,
    "good" : 0
  },
  "users" : {
    "6dICrkbVVJWzVZ00Vq4y9Fm2Qcg2" : true,
    "M0C1XUyboPg5zbgQi24nh3SlJri1" : {
      "isAdmin" : true
    }
  }
},
"branch2" : {
  "address" : "downtown montreal",
  "manager" : "x",
  "rate" : {
    "average" : 0,
    "bad" : 0,
    "good" : 0
  },
  "users" : {
    "M0C1XUyboPg5zbgQi24nh3SlJri1" : true,
    "Z6b5WalkNWZLMVdwGPHi3vSvSRU2" : {
      "isAdmin" : true
    }
  }
}  },  "campaigns" : {
"valentine's day" : {
  "branches" : {
    "branch1" : true
  }
}  }}

和获得branch1的工作代码是：

   ref.child("branches").child("branch1").observe(.value, with: { snapshot in

      let address = snapshot.childSnapshot(forPath: "address").value
      print("\(address)")
   }

它将打印正确的结果（NDG）

安全规则：

{  "rules": {
"Users":{
  "$uid":{
    ".read":"auth.uid == $uid || root.child('Users').child(auth.uid).child('isAdmin').val()==true",
    ".write":"auth.uid == $uid || root.child('Users').child(auth.uid).child('isAdmin').val()==true"


  }

},  "branches":{
"$branchId":{
".read" : "auth.uid == true || root.child('Users').child(auth.uid).child('isAdmin').val()==true || root.child('branches').child($branchId).child('users').child(auth.uid).exists()",
        ".write" :  "auth.uid == true || root.child('Users').child(auth.uid).child('isAdmin').val()==true || root.child('branches').child($branchId).child('users').child(auth.uid).child('isAdmin').val()==true"

}}}}

最佳答案

感谢@vzsg，我发现问题出在权限和规则上。所以我改变了规则，很容易得到结果

{  "rules": {
      "Users":{
        "$uid":{
    ".read":"auth.uid == $uid ||       root.child('Users').child(auth.uid).child('isAdmin').val()==true",
    ".write":"auth.uid == $uid || root.child('Users').child(auth.uid).child('isAdmin').val()==true"


  }

},  "branches":{
        ".read": " root.child('Users').child(auth.uid).child('isAdmin').val()==true" ,
        ".write" :  "root.child('Users').child(auth.uid).child('isAdmin').val()==true ",

"$branchId":{
   ".read": " root.child('branches').child($branchId).child('users').child(auth.uid).exists()",
   ".write" :  "root.child('branches').child($branchId).child('users').child(auth.uid).child('isAdmin').val()==true"

}}  }}

关于ios - 通过观察Firebase中的数据库引用无法获取顶级节点的值，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/41708116/