Question

以下代码使我可以返回当前用户的所有表达式。在此示例中，控制台中显示以下表达式：

但是我不确定如何为当前用户在“表达式”下列出所有标题。理想的结果应该是： KIKKER，CPM2MAN

function f_returnUserDetails(a){
    var key;
    var childData;
    return new Promise(function(resolve, reject) { //return promise
        firebase.database().ref('/users/').orderByChild("uid").equalTo(a).on('value', function (snapshot) {
            snapshot.forEach(function(childSnapshot) {
                key = childSnapshot.key;
                childData = childSnapshot.val();
                resolve([childData, childSnapshot.key]);
            });
        });
    });
};

firebase.auth().onAuthStateChanged(function(user){
    var user = firebase.auth().currentUser;
    var uid = user.uid;
    f_returnUserDetails(uid).then((dbItems) => {
        console.log(dbItems[0].Expressions);
    });
});

Answer 1

通过执行以下操作，您应该获得所需的值：

  firebase.database().ref('/users/').orderByChild("uid").equalTo(a).on('value', function (snapshot) {
      snapshot.forEach(function (childSnapshot) {
          key = childSnapshot.key;
          childData = childSnapshot.val();
          for (v of Object.values(childData.Expressions)) {
              if (v.hasOwnProperty('title')) {
                  console.log(v.title);
              }
          }
      });
  });

Answer 2

您必须构建一个表达式数组并将其返回到函数中

 function f_returnUserDetails(a){
      return firebase.database().ref('/users/' + a + '/Expressions').once('value')
                .then(snapshot => {
                   let expressions = [];
                   snapshot.forEach(childSnapshot =>{
                      let expression = childSnapshot.val();
                      expression.id = childSnapshot.key;
                      expressions.push(expression);
                   }); 
                   return expressions;
                });

 }

稍后您可以使用此功能

f_returnUserDetails(uid).then((dbItems) => {
    console.log(dbItems[0].title);
});

在Firebase中不知道密钥的情况下如何获得孩子的孩子

2 个答案: