Template helper inside template instantiation

Question

Is it possible to call a template helper inside a template instantiation?

For my project, I have created templates for all my custom-styled input elements to make them re-usable. For example, the checkbox would look like:

<template name="myCheckbox">
   <input type="checkbox" id="{{id}}" class="myCheckbox ..." />
</template>

To use it, I simply go:

{{> myCheckbox id="allowEdit"}}

This makes it easy for me to control the look and feel of my inputs across the entire project, as I only need to change the template in order to update all my checkboxes. This works fine, but now I need a template helper to add a "checked" attribute to my checkbox based on the DB. E.g.

Template.myTemplate.helpers({
    checkAllowEdit: function() {
        return (this.allowEdit) ? "checked" : "";
    }
});

{{> myCheckbox id="allowEdit" {{checkAllowEdit}} }}

This doesn't work. Meteor doesn't like me trying to use a helper inside the instantiation. So my question is: Is there any way to call a template helper inside a template instantiation?

Answer 1

For checking a checkbox from a helper, you can use this Blaze feature: have your helper return a boolean and just assign it to your child template's checkbox checked property.

Template.myTemplate.helpers({
    checkAllowEdit: function() {
        return Boolean(this.allowEdit); // Boolean cast may be unnecessary
    }
});

<template name="myTemplate">
  {{!-- things... --}}
  {{> myCheckbox id="allowEdit" checked=checkAllowEdit }}
</template

<template name="myCheckbox">
  <input type="checkbox" id="{{id}}" class="myCheckbox ..." checked={{checked}} />
</template>

A more natural way would be to use a helper in the myCheckbox template instead of the myTemplate one:

<template name="myTemplate">
  {{!-- things... --}}
  {{> myCheckbox id="allowEdit" }}
</template>

Template.myCheckbox.helpers({
    checkAllowEdit: function() {
        return Boolean(this.allowEdit); // Boolean cast may be unnecessary
    }
});

<template name="myCheckbox">
  <input type="checkbox" id="{{id}}" class="myCheckbox ..." checked={{checkAllowEdit}} />
</template>

But I have a feeling you want it in myTemplate on purpose.