Firebase - Following the transit data set tutorial?

Question

I'm pretty new on Firebase, I'm trying to follow this tutorial in Firebase's documentation: https://www.firebase.com/docs/open-data/transit.html

But I am really stuck.. Or better, I am completly lost. Nothing appears on the screen.

<head>
<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=true"></script>
<script src="https://cdn.firebase.com/js/client/1.0.18/firebase.js"></script>
<script src="https://www.firebase.com/resources/js/publicdata/transit.js"></script>
    <script>
    // Lookup all buses on line "X".
    var transitLine = "5";
    var transitRef = new Firebase("https://publicdata-transit.firebaseio.com/ttc");
    var lineIndex = transitRef.child("routes").child(transitLine);

    lineIndex.on("child_added", function (snapshot) {
        var id = snapshot.name();
        transitRef.child("routes").child(id).on("vehicles", busUpdated);
    });
    lineIndex.on("child_removed", function (snapshot) {
        var id = snapshot.name();
        transitRef.child("routes").child(id).off("vehicles", busUpdated);
    });

    function busUpdated(snapshot) {
        // Bus line "X" changed location.
        var info = snapshot.val();
        // Retrieve latitude/longitude with info.lat/info.lon.
    }
</script>
</head>

<body>
<div id="map_canvas" style="position:relative;width:600px;height:400px; border: 1px solid #ccc; margin: 0 auto;"></div>
</body>

Someone knows what am I doing wrong?

If you go to this URL (publicdata-transit.firebaseio.com/ttc), you will see that there is no child named transit. You probably are looking for routes. var lineIndex = transitRef.child("routes").child(transitLine); — Frank van Puffelen
I see. Thanks for the help! Unfortunately, this issue still remains. — h1ghland3r
You register for an event with on("vehicles". I've never seen an event called vehicles and doubt it exists. Do you mean child("vehicles").on("child_added"? — Frank van Puffelen

Frank van Puffelen Frank van Puffelen · Accepted Answer · 2014-08-05T21:32:05

There were two mistakes in your original script:

You are watching the wrong top-level ref (transit instead of routes)
You are listening for a non-existing event (vehicles instead of value)

This code should work better:

// Lookup all buses on line "X".
var transitLine = "5";
var transitRef = new Firebase("https://publicdata-transit.firebaseio.com/ttc");
var lineIndex = transitRef.child("routes").child(transitLine);

lineIndex.on("child_added", function (snapshot) {
    var id = snapshot.name();
    transitRef.child("vehicles").child(id).on("value", busUpdated);
});
lineIndex.on("child_removed", function (snapshot) {
    var id = snapshot.name();
    transitRef.child("vehicles").child(id).off("value", busUpdated);
});

function busUpdated(snapshot) {
    // Bus line "X" changed location.
    var info = snapshot.val();
    console.log(info);
    // Retrieve latitude/longitude with info.lat/info.lon.
}

A fiddle with it: http://jsfiddle.net/tr5P7/

Firebase - Following the transit data set tutorial?

1 Answers