javascript - 如何在 Firebase 中循环浏览快照

Question

我的firebase结构如下:

以下代码搜索用户在选择框中选择的文本 (2019/9/7 AMS MK7777) 并返回 ulds 对象

FBLoad: function(){
            console.log($(".text").text())              

            var ref = firebase.database().ref("flights");
            ref
            .orderByChild("queryDes")
            .equalTo($(".text").text())
            .once("child_added", function(snapshot) {
                console.log(snapshot.val().ulds);
            });
}

我想要完成的是对象的数据由来自 ulds 对象的数据更新需要更新的对象如下:

var positions =  {
    "A": {h_arm:14645, "occupied":0, "ULD":"", "DEST":"", "CNTR":"", "WGHT":0, "TYPE":"", "SHC":[], "RMRK":""},
    "BR": {h_arm:16905,  "occupied":0, "ULD":"", "DEST":"", "CNTR":"", "WGHT":0, "TYPE":"", "SHC":[], "RMRK":""},
    "C": {h_arm:19165, "occupied":0, "ULD":"", "DEST":"", "CNTR":"", "WGHT":0, "TYPE":"", "SHC":[], "RMRK":""},
    "R": {h_arm:19165, "occupied":0, "ULD":"", "DEST":"", "CNTR":"", "WGHT":0, "TYPE":"", "SHC":[], "RMRK":""}
}

最终结果应该是这样的:

var positions =  {
    "A": {h_arm:14645, "occupied":0, "ULD":"", "DEST":"", "CNTR":"", "WGHT":0, "TYPE":"", "SHC":[], "RMRK":""},
    "BR": {h_arm:16905,  "occupied":0, "ULD":"PMC12345QR", "DEST":"DOH", "CNTR":"Q5", "WGHT":2500, "TYPE":"C", "SHC":["RFL","RCM"], "RMRK":"OHG75CMF"},
    "C": {h_arm:19165, "occupied":0, "ULD":"", "DEST":"", "CNTR":"", "WGHT":0, "TYPE":"", "SHC":[], "RMRK":""},
    "R": {h_arm:19165, "occupied":0, "ULD":"PMC77785QR", "DEST":"DOH", "CNTR":"Q5", "WGHT":3540, "TYPE":"C", "SHC":["PIL"], "RMRK":"IND75CMA"}
}

我找不到循环 ulds-object

Answer 1

要循环遍历 uld，请尝试以下操作:

once("value", function(snapshot) {
 snapshot.forEach(function(childSnapshot){
   childSnapshot.forEach(function(uldSnapshot){
     uldSnapshot.forEach(function(nestedUldSnapshot){ 
       console.log(nestedUldSnapshot.val());

        });
      });

首先使用事件value获取数据，然后使用forEach()获取随机id下的数据。然后使用另一个 forEach() 访问 ulds 对象内的数据。