CODEWITHSUNDEEP
node.jsfirebasefirebase-realtime-databasehandlebars.js
Kullis
Kullis

Reputation: 73

Firebase Realtime database with Node.js and Handlebars

I'm trying to make a live updates feed on a Node.js website that would pull the updates from a Firebase realtime database. I manage to make the updates be loaded when the page opens but I'm struggling with making them update in realtime. To be specific: I can't figure out how to pass the database reference object through Handlebars.

So now I pull the updates from the database with:

const getUpdates = () => {
  return new Promise((resolve, reject) => {
    try {
        const ref = firebaseApp.database().ref('liveUpdates');
        resolve(ref.once("value"), ref);
    } catch (e) {
        reject(e);
    }
  });
};

And then render the page:

exports.loadDashboard = (req, res) => {
  getUpdates().then((updates, ref) => {
    const updatesList = updates.val();
    res.render('index', { updatesList, ref });
    return;
  });
};

Then I'd like to do something like this in the .hbs file:

<script>
  var updates = {{{json ref}}};
  updates.on("value" () => {
    //Handle update
  });
</script>

The json Handlebars helper:

json: (content) => {
  return JSON.stringify(content);
}

With this approach the line var updates = {{{json ref}}}; throws an error:

Uncaught SyntaxError: Unexpected token ;

So what am I doing wrong? I haven't worked with Handlebars much before so excuse my ignorance.

Upvotes: 0

Views: 680

Answers (1)

Mladen
Mladen

Reputation: 199

{{{json ref}}} is a Handlebar/Mustache template, not a valid javaScript code. You put that snippet directly inside "a script tag", marking it as JS code.

If you want to evaluate value of Handlebar expression and assign it to a variable using javaScript you may try using compile method. Something like:

var updates = Handlebars.compile('{{{json ref}}}');

After mastering basic Handlebar examples you might also want to take a look at how to pre-compile templates. This is highly recommended for high-load production environments.

Upvotes: 1

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