如何根据日期对 Firebase 用户进行排序？

Question

我试图向非技术人员代表 Firebase 用户。他希望最新的用户位居榜首。我在每个名为 joinDate 的 firebase 用户节点上都有这个键值对。我想以此为基础提取数据。

这里是代码

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++;
                }
            });
        });

我试过了

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

这不起作用，我的数据看起来像这样：- Firebase image

Answer 1

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，因此它们按字典顺序排列。例如，按字典顺序，"01/15/2020" 位于 "21/11/2019" 之前。

要允许按时间顺序排列，您有两个主要选项：

1. 将日期存储为 Firestore 中的实际 Date 值。
2. 将日期存储在字符串中，以确保字典顺序与时间顺序相同，例如"2019-11-21" 在 "2020-01-15" 之前。

另见：

• Firebase query by date string（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