Calling helper functions inside templates

[stnever]

I have several different templates, each in their own file, in which I need to show dates, like the following:

Hello {{= it.name}} on {{= u.d(it.date)}}!

I'd like to format that date, using moment.js, and also add some logic to print unknown when the date is null. Because that happens in a lot of places I created a helper:

var moment = require('moment');
function d(date) {
  if ( date == null ) return 'unknown';
  return moment(date).format('YYYY-MM-DD');
}

But I can't find a way to call that function inside the template. I'm using Node, so I don't want to pollute the global namespace. I even tried putting that in an utility object and require-ing it at the top of my template, to no avail:

{{ var u = require('./utils.js'); }}
Hello {{= it.name}} on {{= u.d(it.date)}}!

FWIW, the generated template function above looks like this:

function anonymous(it) {
  var out=''; var u = require('./utils.js'); out+='\r\n\r\nHello '+( it.name)+' on '+( u.d(it.date))+'!';return out;
}

and the error is

 ReferenceError: require is not defined
      at Context.<anonymous> (test/email-templates/test-dot.js:14:23)

[zlumer]

One option would be to pass the function directly to your template:

Hello {{= it.name }} on {{= it.d(it.date) }}!

var tmpl = anonymous({ name:"John", date:123241, d:require('./utils').d });

[Runaria]

    var dT = require('doT');
    var tpl = {
         tmpl:dT.template('{{=this.helper()}}'),
         helper: function(){
               /* do what you want to do */
         }
    }
    tpl.tmpl(); // render template

or

    // helper functions
    var helper = {
        sum: function(x,y){
            return x+y
        }
    }
    // template
    render = dT.template('{{=this.sum(it.x, it.y)}}');
    // call render
    render.call(helper, {x:5, y:6});

[epoberezkin]

probably can be added to documentation

[epoberezkin]

add to doT 101 #205