What

Use the awesome Handlebars.js both server- and client-side.

Why

DRY. That's why.

Getting Handlebars

The easiest way to get a current distribution of handlebars is to download it from https://github.com/wycats/handlebars.js/downloads.

How

First, grab the copy of handlebars you are using and copy it into vendor/javascripts/handlebars.js. If you want, you can symlink it from your public directory.

In app/controllers/blogs_controller.rb:

BlogsController
  def show
    @blog = Blog.find(params[:id])
  end
end

In app/views/blogs/show.html.hbs:

<article>
  <header>
    <h1>{{{ blog/title }}}</h1>
  </header>
  {{{ blog/body }}}
  <footer>
    by {{{ link_to blog/author/name blog/author }}}
</article>

Usage Gotchas

• Template line numbers may not match stack trace line numbers. This will be resolved upstream.
• Block helpers do not currently work.

HTML-Safety

Rails returns HTML-safe strings, but the string-safety information isn't passed into Handlebars, so Handlebars re-escapes the content. To get around this, use the triple-stash ({{{ ... }}}) when using a Rails helper. See issue 2.

Rails Helpers

Rails helpers obviously do not exist in the client-side JS context. This means that if you use {{{ link_to ... }}}, it can only be run server-side. The solution is to implement a minimal link_to in the client-side. See issue 4 and issue 5.

Credits

Yehuda Katz did all the heavy lifting to get this off the ground, both in terms of writing Handlebars.js and the template handler here. Additional huge props to Charles Lowell for therubyracer, a sine qua non for this project.