How to make a #if with comparison of two variables using handlebars and nodejs

Question

My problem is in creating #if with a comparison with two variables on the .handlebars. page In the edition page I retrieve the data and fill in the fields, however in my select, I need to compare the current id with the ids from the select list, to disable and mark as selected the option that contains the category of the current post I am editing but this comparison does not seem to be allowed this way.

<select name="categoria" id="categoria" class="form-select">
        {{#each categorias}}
                    
             //esse if nao funciona
             {{#if _id == postagem.categoria._id}}
                    <option value="{{postagem.categoria._id}}" selected="true" disabled>
             {{else}}
                    <option value="{{_id}}">{{nome}}</option>
             {{/if}}
        {{else}}
             <option value="0">Nenhuma categoria</option>
        {{/each}}
</select>

That’s the result I want

Answer 1

Register the helper you need and use it. Here’s an example of several helpers I have.

var register = function(Handlebars) {
    var helpers = {
        isSinglePrice: function(arr, options) {
            if(arr.length === 1) {
                return options.fn(this);
            }else{
                return options.inverse(this);
            }
        },
        choosePriceIcon: function(position){
            if(position === 0){
                return "person";
            }else if(position === 1){
                return "group";
            }else if(position === 2){
                return "groups";
            }
        },
        numberFormat: function (value, options) {
            // Helper parameters
            var dl = options.hash['decimalLength'] || 2;
            var ts = options.hash['thousandsSep'] || ',';
            var ds = options.hash['decimalSep'] || '.';

            // Parse to float
            var value = parseFloat(value);

            // The regex
            var re = '\\d(?=(\\d{3})+' + (dl > 0 ? '\\D' : '$') + ')';

            // Formats the number with the decimals
            var num = value.toFixed(Math.max(0, ~~dl));

            // Returns the formatted number
            return (ds ? num.replace('.', ds) : num).replace(new RegExp(re, 'g'), '$&' + ts);
        }
    };

    if (Handlebars && typeof Handlebars.registerHelper === "function") {
        for (var prop in helpers) {
            Handlebars.registerHelper(prop, helpers[prop]);
        }
    } else {
        return helpers;
    }

};

module.exports.register = register;
module.exports.helpers = register(null);

Just create as many helper methods as you need to make the comparisons you need and use it the way you think best.

And here as you use:

var exphbs = require('express-handlebars');

var handlebars = exphbs.create({
    layoutsDir: path.join(__dirname, "views/layouts"),
    partialsDir: path.join(__dirname, "views/partials"),
    defaultLayout: 'index',
    extname: 'hbs',
    helpers: require("./helpers/hbs.js").helpers
});

EDIT: Here is an example of how you assign the handlebars engine, with the helpers registered above:

const app = express();
app.engine('hbs', handlebars.engine);
app.set('view engine', 'hbs');
app.set('views', './views')

Now it’s up to you. I hope I’ve helped.