成功登录后 firebase.auth().CurrentUser.uid 为 null [英] firebase.auth().CurrentUser.uid is giving null after successful login

问题描述

我使用了 firebase 登录.它正在成功登录.我在登录页面配置文件中有四个页面，包括销售、购买和关于我们.当我在个人资料和销售页面中检索当前用户的 uid 值时.但是我在购买页面上显示为空，为什么会这样?

I have made use of firebase login. It is logging in successfully. I have four pages inside login page profile, sell, buy and about us. When I am retrieving the value of current user's uid in profile and sell page. But i am getting null in buy page why is it so?

JS对于用户页面

function save_user()
      {
     const uid = document.getElementById('user_id');
            const userpwd = document.getElementById('user_pwd');
            const btnregister=document.getElementById('btn-action');
            //btnregister.addEventListener('click', e=>
            //{
            const email=uid.value;
            const pass=userpwd.value;
            firebase.auth().signInWithEmailAndPassword(email, pass).catch(function(error) {
    // Handle Errors here.
    var errorCode = error.code;
    console.log(error.Message);

});
firebase.auth().onAuthStateChanged(function(user) {
  if(user) {
    window.location='userpage.html'; 
  }
});

JS

对于 firebase.auth().currentUser.uid 显示空代码的购买页面

for buy page where firebase.auth().currentUser.uid is showing null code

var fbRef = firebase.database().ref().child("Sell_Products");
    var user = firebase.auth().currentUser.uid; 
alert(user);    /*Here it's showing null
fbRef.on("child_added", snap => {
    var key=snap.key;
    alert('HEllo');
    alert(key);
    var name = snap.child("name").val();
    var price = snap.child("price").val();
    var category = snap.child("category").val();
    var description = snap.child("description").val();
    var image = snap.child("image").val();
    $("#ex-table").append("<tr><td><a href="auction.html?itemKey="+key+""><img src=" + image + "/img></a></td><td>" + name + "</td><td>" + price + "</td><td>" + category + "</td><td>" + description + "</td></tr>" );
});

推荐答案

我也遇到过这样的问题.实际上，在 auth 未初始化之前，它无法显示一些数据，但是当我们使用 firebase.auth().CurrentUser 时，它甚至在 auth 初始化之前获取数据.您可以在代码中设置超时，直到身份验证完全初始化.

I also encountered such problem. Actually, until the auth is not initialized, it cant show some data but when we use firebase.auth().CurrentUser, it fetches data even before the auth is initialized. You can set a timeout in the code until the auth is completely initialized.

我使用这种方法来获取数据.

I used this approach to get the data.

const authPromise=()=>{
    return new Promise((resolve,reject)=>{
        const user = firebase.auth().currentUser;
        console.log(user.email)
    })
}

setTimeout(authPromise,2000)

这篇关于成功登录后 firebase.auth().CurrentUser.uid 为 null的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！