通过Firebase管理访问深度数据

Question

如何通过Firebase管理访问深度数据？

数据：

{
    "keyboards": {
        "StartKeyboard": [
            "KeyboardA",
            "KeyboardB",
            "KeyboardC"
        ],
        "SecendKeyboard": {
            "parent": "StartKeyboard",
            "childs": [      //*** I need to get this childs: [] ***
                "Keyboard1",
                "Keyboard2",
                "Keyboard3"
            ]
        }
    }
}

当我使用下面的代码时，输出中的所有数据

const ref = db.ref('/');    All Data
ref.on("value", function (snapshot) {
    console.log(snapshot.val());
  });

当我使用下面的代码时，输出keyboards 中有的子类

 const ref = db.ref('keyboards');   // inside of Keyboards
    ref.on("value", function (snapshot) {
        console.log(snapshot.val());
      });

但我不知道如何获得childs of SecendKeyboard/childs。我指的是Keyboard1、Keyboard2和Keyboard3的数组。谢谢。

Answer 1

要获得键盘子级：

const ref = db.ref('keyboards/SecendKeyboard/childs');
ref.on("value", function (snapshot) {
    console.log(snapshot.val());
});

或者：

const ref = db.ref('keyboards/SecendKeyboard');
ref.on("value", function (snapshot) {
    console.log(snapshot.child("childs").val());
});

或

const ref = db.ref('keyboards');
ref.on("value", function (snapshot) {
    snapshot.forEach(function(childSnapshot) {
        console.log(snapshot.val()); // prints StartKeyboard and SecendKeyboard
        if (snapshot.child("SecendKeyboard").exists()) {
            console.log(snapshot.child("SecendKeyboard").val());
        }
    })
});