Meteor: Access Template Helper (or variable) from another helper

Question

How can I reference a template helper from another one? For example...

Template.XXX.helpers({
    reusableHelper: function() {
        return this.field1 * 25 / 100; //or some other result
    },
    anotherHelper: function() {
        if (this.reusableHelper() > 300) //this does not work
            return this.reusableHelper() + ' is greater than 300'; 
        else
            return this.reusableHelper() + ' is smaller than 300';
    }
});

I have also tried Template.instance().__helpers.reusableHelper - all with no luck.

Alternatively is there a way to define reactive Template instance variables?

XXX is a sub-template that renders multiple times on the same page.

Answer 1

You can but only with global template helpers.

Blaze._globalHelpers.nameOfHelper()

Here is an example calling Iron:Router's pathFor global helper.

Template.ionItem.helpers({
  url: function () {
    var hash = {};
    hash.route = path;
    hash.query = this.query;
    hash.hash = this.hash;
    hash.data = this.data;
    var options = new Spacebars.kw(hash);

    if (this.url){
      return Blaze._globalHelpers.urlFor(options)
    } else if( this.path || this.route ) {
      return Blaze._globalHelpers.pathFor(options)
    }
  }
});

EDIT: To your second question. You can call the same template as many times as you like on a page and pass different data attributes directly into it and/or use #each block template wrapper to iterate over data. #each will call a template many times giving it a different data context each time.

#each Example

<template name="listOfPosts">
  <ul>
    {{#each posts}}
      {{>postListItem}} <!--this template will get a different data context each time-->
    {{/each}}
  </ul>
</template>

Attributes Example

<template name="postDetails">
  {{>postHeader title="Hello World" headerType="main" data=someHelper}}
  {{>postHeader title="I am a sub" headerType="sub" data=newHelper}}
  {{>postBody doc=bodyHelper}}
</template>