如何使用密钥检索firebase中的子数据？

Question

我是firebase的新手。我想要获取子数据和密钥。我在nodejs Environment中尝试了以下代码。

  var firebase = require("firebase");

    firebase.initializeApp({
       databaseURL: "https://some.firebaseio.com/"
    });


    var customer = firebase.database().ref().child('customer');

    const fname = "name";
    const lname = "title";
    customer.orderByChild("partnerFirstName").equalTo(fname).on('child_added', function (snapshot) {
       console.log(snapshot.val());

       var fn = snapshot.val().partnerFirstName;

       var custdata = snapshot.val();

       console.log(custdata);
       console.log("FirstName:"+fn);

       if (custdata.partnerFirstName === fn) {
         console.log(custdata);

       }


     });

输出如下

    {
      createdAt: '2018-03-20T23:25:35.212Z',
      partnerEmail: '[email protected]',
      partnerFirstName: 'name',
      partnerGender: 'male',
      partnerLastName: 'title',
      partnerPhone: '444-602-4444',
      profilePicture: 'assets/profile_icon.png',
      uid: 'x99wl8kkmJSENpNdVMXTXCh7amy2' }
      FirstName: name

在这种情况下，我们没有获得记录的键值，但是firstname没有任何错误。

但是，当我们尝试以下代码时，关键是数据，但是firstname是未定义的

 var customer = firebase.database().ref().child('customer');

        const fname = "Name";
        const lname = "Title";
        customer.orderByChild("partnerFirstName").equalTo(fname).on('value', function (snapshot) {
           console.log(snapshot.val());

           var fn = snapshot.val().partnerFirstName;

           var custdata = snapshot.val();

           console.log(custdata);
           console.log("FirstName:"+fn);
           if (custdata.partnerFirstName === fn) {
             console.log(custdata);

           }


         });

输出如下

{ '-L84iSPyr9bPvnJZ6BgV':
   { 
     createdAt: '2018-03-20T23:25:35.212Z',
     partnerEmail: '[email protected]',
     partnerFirstName: 'name',
     partnerGender: 'male',
     partnerLastName: 'title',
     partnerPhone: '444-602-4444',
     profilePicture: 'assets/profile_icon.png',
     uid: 'x99wl8kkmJSENpNdVMXTXCh7amy2' } }
     FirstName: undefined

如何获取子数据和密钥？

Answer 1

你应该用你的代码替换

customer.orderByChild("partnerFirstName").equalTo(fname).on('value', 
    function (snapshot) {

       var snap = snapshot.val();
       var key = Object.keys(snap);
       var custdata = snap[key];
       var fn = snap[key].partnerFirstName;

       if (custdata.partnerFirstName === fn) {
         console.log(custdata);
       }
 });

返回钥匙和孩子

Answer 2

要获取密钥，请尝试以下操作：

var ref = firebase.database().ref("customer").orderByChild("partnerFirstName").equalTo(fname);
ref.once("value").then(function(snapshot) {
snapshot.forEach(function(child){
var key = child.key; 
var partnerName=child.val().partnerFirstName;

  });
});

在上面，你在customer的子元素内迭代，然后使用var key = child.key;检索密钥

Answer 3

感谢大家。我成功解决了这段代码的问题。我的主要动机是使用上面的代码通过firebase云函数获取json格式。它工作正常。我成功搜索了url中的firstname和lastname并获取了相应的记录。

exports.getCustomerbyname2 = functions.https.onRequest((req, res) => {
    res.header('Content-Type', 'application/json');
    res.header('Access-Control-Allow-Origin', '*');
    res.header('Access-Control-Allow-Headers', 'Content-Type');


    if (req.method === 'OPTIONS') {
      res.status(204).send('');
    }
    const fname = req.query.fname;
    const lname = req.query.lname;

    var customer=admin.database().ref().child('customer'); 
    customer.on('child_added', function (snapshot) {
        var fname1 = snapshot.val().partnerFirstName; 
        var lname1 = snapshot.val().partnerLastName; 

       customer.orderByChild('partnerFirstName').equalTo(fname).once('value', function(snapshot) {


            var arr=[];
            if (fname1 === fname && lname1===lname) {
                arr.push(snapshot.val());
                console.log(snapshot.val());
                res.status(200).json({ customer: arr});


            }else{
                res.status(200).send('ERROR : ' + errorObject);

            }

        },function(errorObject){
            console.log("The read failed: " + errorObject.code);
           // res.status(200).send('ERROR : ' + errorObject);
        });

    });

});