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Question

我刚刚开始使用firebase，我是node.js环境的新手 我试图发送从我的数据库中获取数据我得到了这个使用此代码

 var country = sessionStorage.countryname;
 var ref = firebase.database().ref('posts/country/' + country + '/')

 ref.on('value', function(snapshot) {
     snapshot.forEach(function(keysSnapshot) {
         var keys = keysSnapshot.val();

         console.log('keys', keys);

     })
 }); 

我获得了密钥中的所有数据，但我不知道如何访问它，例如我想获得每个帖子的年龄和first_name ..这是我在控制台日志中得到的

这是我的数据库

这是json代码

{
  "country" : {
    "Algeria" : {
      "844kh2QXDHgw7i4KBvULpCSO5KE2" : {
        "-L9MvZxV2bVjcuKGZx-2" : {

          "age" : "26",
          "first_name" : "jack",

          "gender" : "female",

          "home_adress" : "2222222222222222222222222222",

          "last_name" : "anonyo",

        },
        "-L9Mvpnyx1f9DDDygJcG" : {

          "age" : "29",

          "first_name" : "jazmine",

          "gender" : "female",

          "home_adress" : "2222222222222222222222222222",

          "last_name" : "anony",

        }
      },
      "QgWbVLqInga3JRNuzzlZBCzwkws2" : {
        "-L9ES58GkQcZGywqpIWY" : {

          "age" : "29",

          "first_name" : "jazmine",

          "gender" : "female",

          "home_adress" : "2222222222222222222222222222",

          "last_name" : "anony",

        }
      }
    },

    "england" : {
      "jdL079kwJUQSBzKE7aNIPInPEHX2" : {
        "-L925-sxlxsF5k9LZFHp" : {

           "age" : "29",

          "first_name" : "jessica",

          "gender" : "female",

          "home_adress" : "2222222222222222222222222222",

          "last_name" : "anony",
        }
      }
    }
  }
}

Answer 1

如果您想迭代所有用户：

var objectKeys = Object.keys(keys);
for(x=0; x < objectKeys.length; x++){
     var currentKey = objectKeys[x];
     var userData = keys.currentKey; //Here you have all the data
     console.log(userData);
     //Now access the first_name property
     var firstName = userData.first_name;
}

我没有测试它，但它应该工作。

Answer 2

使用snapshot.val()[844kh2QXDHgw7i4KBvULpCSO5KE2][-L9MvZxV2bVjcuKGZx-2][age]获取。请参阅文档Read and Write Data on the Web

var starCountRef = firebase.database().ref('posts/' + postId + '/starCount');
starCountRef.on('value', function(snapshot) {
  updateStarCount(postElement, snapshot.val());
});

Answer 3

好的，这就是我如何使用var country = sessionStorage.countryname;

database.ref('posts/country/'+country).once('value').then(function(snapshot) {
  var country = snapshot.key ;

  snapshot.forEach(function(snapshot1) {
    console.log(snapshot1.key); // 
    snapshot.forEach(function(snapshot2) {
      console.log(snapshot2.key); // 

      snapshot2.forEach(function(snapshot3) {
        console.log(snapshot3.key);
        console.log(snapshot3.val().first_name)
    });
  });
});
});

感谢这里的坦率回答How to retrieve nested child value in Firebase database using javaScript?     ty帮助人们