cant synchronize correctly with realtime database of firebase

Question

As part of my studies I need to develop web-app (javasript language) Where we work with firebase realtime database.

currently inside the database,I have a tree of users objects that representing all the users who registered to the system. And what I'm trying to do is a simple user login function.

After the user entered his username and his password, I created an array to enter the entire user tree from a database. The problem is that when im calling the function from the Firebase it's not enough to ended.. and what happens is that the array remains empty and you can not verify that the user is registered on the system. now I have used a temporary solution that Im using setTimeout function,I understand that this is wrong programming, and also i do not want the user to wait 2 seconds every time he wants to login to the system.

Can someone please help me? how to do it right without the setTimeout function? I want that the function of the Firebase ends so only then start with the Authentication process.

Here is the code I wrote so far,

        var correntUser;
        var userlist = []; 
        var usersRef = database.ref('users');

        // Query that inserts all users keys and names to an array.

        usersRef.orderByChild("username").on("child_added", function(snapshot) 
        { 
            userlist.push({userKey:snapshot.key,username:snapshot.val().username,password:snapshot.val().password});
        });

        setTimeout(function() 
        {
            //check if user exist in userlist.
            for(var i=0; i<userlist.length;i++)         
                if (userlist[i].username == usernameArg && userlist[i].password == passwordArg)
                    correntUser = userlist[i].userKey;

            if(correntUser == undefined)            
            {
                //check if  undefined
                alert("wrong username or password");
                document.getElementById("username").value = "";
                document.getElementById("password").value = "";
                return;
            }
            mainPage.addHeader();
        },2000);

thank you all.

score 1 · Answer 1 · edited May 23 '17 at 12:34

There is no need to manually check all users and see if there is a match with the attempted login credentials when Firebase provides built-in authentication. Password-based accounts require email addresses, although you can combine the username with any domain name to satisfy that requirement as suggested here.

You did not explain what your database structure looks like under the users path, but one way to handle that is to incorporate the user's unique id that gets returned as part of the createUserWithEmailAndPassword password:

function createAccount(email, password) {
    firebase.auth().createUserWithEmailAndPassword(email, password)
    .then(function(userData) {
        // account created successfully
        usersRef.child(userData.uid).set({
            email: email,
            creation_date: new Date(),
            ...
        })
    }
    .catch(function(error) {
        ...
    })
}

Then for login attempts:

function login(email, password) {
    firebase.auth().signInWithEmailAndPassword(email, password)
    .then(function(userData) {
        // login successful
        mainPage.addHeader();
    })
    .catch(function(error) {
        alert("wrong username or password");
        document.getElementById("username").value = "";
        document.getElementById("password").value = "";
    })
}

cant synchronize correctly with realtime database of firebase

1 Answers1