如何根据日期对Firebase用户进行排序？

我正在尝试向非技术人员代表Firebase用户。他想把最新的用户放在首位。我在名为joinDate的每个Firebase用户节点上都有这个键值对。我想基于此提取数据。

这是代码

ref.on('value',function(snapshot) {
var i = 1;
snapshot.forEach(function(childsnapshot) {
var childData = childsnapshot.val();
console.log(childData);
if (childsnapshot) {
var emailText = childsnapshot.child("userProfile/email").val();
var joinDateText = childsnapshot.child("joinDate").val();
var currentPhyxText = childsnapshot.child("userProfile/currentPhyx").val();
var nameText = childsnapshot.child("userProfile/name").val();
var lastNameText = childsnapshot.child("userProfile/lastname").val();
var progressText = childsnapshot.child("userProfile/progress");
var lastSeenDateText = childsnapshot.child("userProfile/score/lastDate").val();
var StringifiedProgressText = JSON.stringify(progressText);
var email = document.createElement("h4");
var number = document.createElement("h4");
var joinDate = document.createElement("h6");
var currentPhyx = document.createElement("h6");
var name = document.createElement("h6");
var lastName = document.createElement("h6");
var lastDate = document.createElement("h6");
var lowbackData = document.createElement("h6");
var progress = document.createElement("h6");
var br = document.createElement("br");
email.style.display = "inline";
number.style.display = "inline";
lastName.style.display = "inline";
name.style.display = "inline";
joinDate.textCOntent= "Join Date : " + joinDateText;
currentPhyx.textCOntent= "Current Phyx : " + currentPhyxText;
number.textCOntent= i+") ";
email.textCOntent= emailText;
name.textCOntent= "Name : " + nameText;
lastName.textCOntent= " " + lastNameText;
lastDate.textCOntent= "Last Seen Date : " + lastSeenDateText;
progress.textCOntent= "Progress : " + StringifiedProgressText;
progress.textCOntent= progress.textContent.replace(/{/g,"");
progress.textCOntent= progress.textContent.replace(/}/g,"");
progress.textCOntent= progress.textContent.replace(/"/g,"");
progress.textCOntent= progress.textContent.replace(/,/g," • ")
document.body.appendChild(number);
document.body.appendChild(email);
document.body.appendChild(joinDate);
document.body.appendChild(currentPhyx);
document.body.appendChild(name);
document.body.appendChild(lastName);
document.body.appendChild(lastDate);
document.body.appendChild(progress);
document.body.appendChild(br);
i++;
}
});
});


我尝试做

ref.orderByChild("joinDate").on('value',function(snapshot) {
...
...
}


这不起作用，或者我的数据看起来像这样：-
Firebase image

您的joinDate属性以dd/MM/yyyy格式保存字符串值。由于它们是字符串值，因此按字典顺序对其进行排序。并且按字典顺序，例如"01/15/2020"在"21/11/2019"之前。

要允许按时间顺序排序，您有两个主要选项：

1. 将日期作为实际Date值存储在Firestore中。


2. 将日期存储在字符串中，以确保其字典顺序与时间顺序相同，例如"2019-11-21"在"2020-01-15"之前。

另请参阅：

• Firebase query by date string（适用于实时数据库，但问题和解决方案完全相同）


• How to retrieve data from firebase where the value of a date is 1 month ago from current date


• How does Firestore query operation strings treat different data types?


• How to order data from Firestore in Flutter,orderBy not ordering correct