Question

firebase数据结构是

{
  "eventAttendees" : {
    "fm" : {
      "1" : "David",
      "2" : "Alice"

    }
  },
  "events" : {
    "fm" : {
      "date" : "2017-06-16",
      "name" : "Firebase Meetup"
    },
    "gm" : {
      "date" : "2017-08-12",
      "name" : "Meet Linh"
    }
  },
  "users" : {
    "1" : {
      "email" : "david@gmail.com",
      "name" : "David"
    },
    "2" : {
      "email" : "alice@gmail.com",
      "name" : "Alice"
    },
    "10" : {
      "email" : "khanh@gmail.com",
      "name" : "Khanh"
    }
  }
}

我想找到所有转到fm活动的用户。这是我的代码：

let ref = Database.database().reference()
ref.child("eventAttendees/fm").observe(.value, with: { (snapshot) in
           print (snapshot.key)
            ref.child("users/\(snapshot.key)").observeSingleEvent(of: .value, with: { (userSnapshot) in
                let content = userSnapshot.value as? [String : AnyObject] ?? [:]
                print(content)
            })
        })

我按照本教程https://youtu.be/Idu9EJPSxiY?t=3m14s，

根据教程snapshot.key，应返回“1”，“2”，以便ref.child("users/\(snapshot.key)")为ref.child("users/1")

但在我的代码中，snapshot.key返回“fm”和ref.child("users/\(snapshot.key)")将为ref.child("users/fm")

我的代码中的问题在哪里？

Answer 1

在eventAttendees/fm下，您有多个孩子。因此，您还需要在代码中循环遍历这些子节点：

let ref = Database.database().reference()
ref.child("eventAttendees/fm").observe(.value, with: { (snapshot) in
    for child in snapshot.children.allObjects as [FIRDataSnapshot] {
        print (child.key)
        ref.child("users/\(child.key)").observeSingleEvent(of: .value, with: { (userSnapshot) in
            let content = userSnapshot.value as? [String : AnyObject] ?? [:]
            print(content["name"])
        })
    }
})

加入Firebase数据库

1 个答案: