Question

I have the following data that I am trying to feed into a Handlebar template

{
    "set-group": [
        {
            "label": "Source Data",
            "type": "select",
            "options": [
                {
                    "value": "Default Selections"
                },
                {
                    "value": "Other Selections"
                }
            ]
        },
        {
            "label": "Scale",
            "type": "radio",
            "options": [
                {
                    "value": "log",
                    "label": "Log",
                    "groupname": "group2"
                },
                {
                    "value": "linear",
                    "label": "Linear",
                    "groupname": "group2"
                }
            ]
        }
    ]
}

I created and registered 2 Partials, one that templates “selects” form elements and one that templates “radio” inputs. I cannot know what type of form element will be in the data so I need some sort of helper that checks if type == select and applies the appropriate partial for the select. I am having trouble with creating such a helper.

I was thinking of replacing type=select in the data to just select=true and just check for true/false using the if/else helper but I would rather keep the format standardized

Any ideas?

Answer 1

I ended up using this helper

// Comparison Helper for handlebars.js
// Pass in two values that you want and specify what the operator should be
// e.g. {{#compare val1 val2 operator="=="}}{{/compare}}

Handlebars.registerHelper('compare', function(lvalue, rvalue, options) {

    if (arguments.length < 3)
        throw new Error("Handlerbars Helper 'compare' needs 2 parameters");

    operator = options.hash.operator || "==";

    var operators = {
        '==':       function(l,r) { return l == r; },
        '===':      function(l,r) { return l === r; },
        '!=':       function(l,r) { return l != r; },
        '<':        function(l,r) { return l < r; },
        '>':        function(l,r) { return l > r; },
        '<=':       function(l,r) { return l <= r; },
        '>=':       function(l,r) { return l >= r; },
        'typeof':   function(l,r) { return typeof l == r; }
    }

    if (!operators[operator])
        throw new Error("Handlerbars Helper 'compare' doesn't know the operator "+operator);

    var result = operators[operator](lvalue,rvalue);

    if( result ) {
        return options.fn(this);
    } else {
        return options.inverse(this);
    }
  });

Source: http://doginthehat.com.au/2012/02/comparison-block-helper-for-handlebars-templates/