CODEWITHSUNDEEP
javascriptfirebasefirebase-realtime-database
VPY
VPY

Reputation: 463

Firebase : First Argument contains undefined in property

In my webpage I am trying to do a query from one firebase db and an update on another firebase db.

The issue is when I try to do an update on the second database I get an error saying that the property is undefined.

I have put several console log and I am sure they contain a numeric value so I am not sure why firebase is complaining that the property is undefined.

My HTML Page

<html>
    <head>
    <meta charset="utf-8">
    <title>
    Firebase Test
    </title>
    </head>
    <style>
    .alright
    {
        text-align: left;
        border: 1px solid black;
        border-collapse: collapse;
    }
    </style>
    <body>


<input type="button" value="SHUFFLE" onClick="window.location.reload()">

<table class="alright">
<tr>
<th><h1>Niyant</h1></th>
<th><h1>Varun</h1></th>
</tr>

<!--<tr>
<th><h1 id="niyantscoretag"></h1></th>
<th><h1 id="varunscoretag"></h1></th>
</tr>-->
<tr>
<td><h2 id="ns">0</td>
<td><h2 id="vs">0</td>
</tr>
<tr>
<td><h3 id="nrank">0</td>
<td><h3 id="vrank">0</td>
</tr>
<tr>
<td><img id="imgtag1"/></td>
<td><img id="imgtag2"/></td>
</tr>
<tr>
<td><h2>Winner is</h2></td>
<td><img id="imgtag3"/></td>
</tr>
</table>


    <script src="https://www.gstatic.com/firebasejs/3.9.0/firebase.js"></script>
    <script>

      var config = {
        apiKey: "AIzaSyAXpEHm1uLfRLS-6QCun1iVioquEmpmbAI",
        authDomain: "helloworld-3c2e7.firebaseapp.com",
        databaseURL: "https://helloworld-3c2e7.firebaseio.com",
        projectId: "helloworld-3c2e7",
        storageBucket: "helloworld-3c2e7.appspot.com",
        messagingSenderId: "103101977379"
      };
      firebase.initializeApp(config);

      var otherAppConfig = {

    apiKey: "AIzaSyC3UBiLaBJoW0vfY5xJgtFWV_zdKl9vfWo",
    authDomain: "scoringdev-b5ede.firebaseapp.com",
    databaseURL: "https://scoringdev-b5ede.firebaseio.com",
    projectId: "scoringdev-b5ede",
    storageBucket: "scoringdev-b5ede.appspot.com",
    messagingSenderId: "123331117443"

};

var database1 = firebase.initializeApp(config,"primary");
var database1_database = database1.database();

var database2 = firebase.initializeApp(otherAppConfig, "secondary");
var database2_database = database2.database();


/************HERE**********/
var nscoref = database2_database.ref('Niyant/Score');
var vscoref = database2_database.ref('Varun/Score');
var vscore,nscore,vscoreincremented,nscoreincremented;

nscoref.on('value', 
                function(snapshot){


                                        nscore = snapshot.val();
                                        nscoreincremented = nscore + 1;
                                        console.log("nscore = "+nscore);
                                        console.log("nscoreincremented = "+nscoreincremented);

                                   }
        );

vscoref.on('value', 
                function(snapshot){



                                        vscore = snapshot.val();
                                        vscoreincremented = vscore + 1;
                                        console.log("vscore = "+vscore);
                                        console.log("vscoreincremented = "+vscoreincremented);

                                   }
        );




var URLPath1,URLPath2,nsv,vsv;


var num1 = Math.floor(Math.random() * 100) + 1;
var num2 = Math.floor(Math.random() * 100) + 1;

if(num1 < num2)
{
    database2_database.ref('Niyant').set({Score: nscoreincremented});
}
else if(num1 > num2)
{
    database2_database.ref('Varun').set({Score: vscoreincremented});
}


var imgref1 = database1_database.ref(num1+'/Location');
var imgref2 = database1_database.ref(num2+'/Location');
var imgref1_name = database1_database.ref(num1+'/Name');
var imgref2_name = database1_database.ref(num2+'/Name');


imgref1.on('value', 
                function(snapshot){

                                        URLPath1 = snapshot.val();
                                        console.log(URLPath1);
                                        console.log(snapshot.val());

                                        document.getElementById("imgtag1").src = URLPath1;
                                        document.getElementById("nrank").innerText = 'Rank '+num1;
                                        if(num1 < num2)
                                        {
                                            document.getElementById("imgtag3").src = URLPath1;


                                        }

                                   }
        );

imgref2.on('value', 
                function(snapshot){

                                        URLPath2 = snapshot.val();
                                        console.log(URLPath2);


                                         document.getElementById("imgtag2").src = URLPath2;
                                         document.getElementById("vrank").innerText = 'Rank '+num2;
                                         if(num2 < num1)
                                        {
                                            document.getElementById("imgtag3").src = URLPath2;

                                        }
                                  }

        );

imgref1_name.on('value', 
                function(snapshot){

                                        URLPath1_name = snapshot.val();
                                        console.log(URLPath1_name);
                                        console.log(snapshot.val());

                                        document.getElementById("ns").innerText = URLPath1_name;


                                   }
        );

imgref2_name.on('value', 
                function(snapshot){

                                        URLPath2_name = snapshot.val();
                                        console.log(URLPath2_name);


                                         document.getElementById("vs").innerText = URLPath2_name;

                                   }
        );


    </script>



    </body>
    </html>

This is from the Chrome console.

enter image description here

The problematic updates are commented out with "***HERE****" in the source for reference.

Can someone help me out here ?

Upvotes: 2

Views: 3831

Answers (1)

Frank van Puffelen
Frank van Puffelen

Reputation: 598728

Data is read from Firebase asynchronously. Your code doesn't cater for that, which leads to you trying to set a score before it's actually been loaded.

The solution is to properly synchronize access to the data: first ensure that everything is loaded, only then update the score.

var nscoref = database2_database.ref('Niyant/Score');
var vscoref = database2_database.ref('Varun/Score');
var vscore,nscore,vscoreincremented,nscoreincremented;

function updateScore() {
    var num1 = Math.floor(Math.random() * 100) + 1;
    var num2 = Math.floor(Math.random() * 100) + 1;
    if(num1 < num2) {
        database2_database.ref('Niyant').set({Score: nscoreincremented});
    }
    else if(num1 > num2) {
        database2_database.ref('Varun').set({Score: vscoreincremented});
    }
}

nscoref.on('value', function(snapshot){
    nscore = snapshot.val();
    nscoreincremented = nscore + 1;
    if (nscoreincremented && vscoreincremented) {
        updateScore();
    }
});

vscoref.on('value', function(snapshot){
    vscore = snapshot.val();
    vscoreincremented = vscore + 1;
    if (nscoreincremented && vscoreincremented) {
        updateScore();
    }
});

Upvotes: 5

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