ios - Swift 检索 Firebase 数据

Question

Firebase 数据库中的以下数据:

{
  "schedule": {
      "Week 1": {
        "active": "true"
      },
      "Week 2": {
        "active": "true"
      },
      "Week 3": {
        "active": "false"
      },
      "Week 4": {
        "active": "true"
      },  
      ...
   }
}

我想检索所有 active 只为 true 的星期。我正在这样设置 Firebase 引用:

ref = FIRDatabase.database().reference(withPath: "Schedule")

然后执行以下操作:

ref.observeSingleEvent(of: .value, with: { snapshot in
        //
        print("Count: ", snapshot.childrenCount)

        for _ in snapshot.children {
                print("\(snapshot.value)")
        }

    })

产生以下输出:

Optional({
      "Week 1" =     {
           active = 1;
       };
       "Week 2" =     {
           active = 1;
       };
       "Week 3" =     {
           active = 0;
       };
       "Week 4" =     {
           active = 1;
       };
       ...
}

有人可以建议我如何只获取 active 设置为 true 的周数，这需要加载到字符串类型的数组中:

var weeksActive = [String]()

Answer 1

为此，您可以像这样使用 queryOrdered(byChild:) 和 queryEqual(toValue:)。

let ref = FIRDatabase.database().reference(withPath: "Schedule").queryOrdered(byChild: "active").queryEqual(toValue : true)

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

    print("Count: ", snapshot.childrenCount)
    for child in snapshot.children {
        print("\((child as! FIRDataSnapshot).value)")
        //To get week you need to access key
        print("\((child as! FIRDataSnapshot).key)")
    }
})