Use handlebars.js templates with the asset pipeline and sprockets

Are your handlebars.js templates littering your Rails views with script tags? Wondering why the nifty Rails 3.1 asset pipeline streamlines all your Javascript except for your Handlebars templates? Wouldn't it be nice to have your Handlebars templates compiled, compressed, and cached like your other Javascript?

Yea, I think so too. That is why I wrote handlebars_assets. Give your Handlebars templates their own files (including partials) and have them compiled, compressed, and cached as part of the Rails 3.1 asset pipeline!

Using sprockets with Sinatra or another framework? handlebars_assets works outside of Rails too (as of v0.2.0)

handlebars.js

handlebars_assets is packaged with v1.0.rc.1 of handlebars.js.

Installation with Rails 3.1+

Load handlebars_assets in your Gemfile as part of the assets group

group :assets do
  gem 'handlebars_assets'
end

Installation without Rails 3.1+

handlebars_assets can work with earlier versions of Rails or other frameworks like Sinatra.

Load handlebars_assets in your Gemfile

gem 'handlebars_assets'

Add the HandlebarsAssets.path to your Sprockets::Environment instance. This lets Sprockets know where the Handlebars JavaScript files are and is required for the next steps to work.

env = Sprockets::Environment.new

require 'handlebars_assets'
env.append_path HandlebarsAssets.path

Compiling your Javascript templates in the Rails asset pipeline

Require handlebars.runtime.js in your Javascript manifest (i.e. application.js)

//= require handlebars.runtime

If you need to compile your Javascript templates in the browser as well, you should instead require handlebars.js (which is significantly larger)

//= require handlebars

Precompiling

handlebars_assets also works when you are precompiling your assets. If you are deploying to Heroku, be sure to read the Rails guide and in your config/application.rb set:

config.assets.initialize_on_precompile = false

Templates directory

You should locate your templates with your other assets, for example app/assets/javascripts/templates. In your Javascript manifest file, use require_tree to pull in the templates

//= require_tree ./templates

The template file

Write your Handlebars templates as standalone files in your templates directory. Organize the templates similarly to Rails views.

For example, if you have new, edit, and show templates for a Contact model

templates/
  contacts/
    new.hbs
    edit.hbs
    show.hbs

Your file extensions tell the asset pipeline how to process the file. Use .hbs to compile the template with Handlebars.

If your file is templates/contacts/new.hbs, the asset pipeline will generate Javascript code

1. Compile the Handlebars template to Javascript code
2. Add the template code to the HandlebarsTemplates global under the name contacts/new

You can then invoke the resulting template in your application's Javascript

HandlebarsTemplates['contacts/new'](context);

The template namespace

By default, the global Javascript object that holds the compiled templates is HandlebarsTemplates, but it can be easily renamed. Another common template namespace is JST. Just change the template_namespace configuration option when you initialize your application.

HandlebarsAssets::Config.template_namespace = 'JST'

Partials

If you begin the name of the template with an underscore, it will be recognized as a partial. You can invoke partials inside a template using the Handlebars partial syntax:

Invoke a {{> partial }}

Important! Handlebars does not understand nested partials. To support them, partials are named based on their path using _ instead of / (skid => slash). So given:

templates/
  _form.hbs
  contacts/
    _form.hbs
  todos/
    _form.hbs

You will get three partials named _form, _contacts_form, and _todos_form; note that the partials begin with _.

Using another version of handlebars.js

Occasionally you might need to use a version of handlebars.js other than the included version. You can set the compiler_path and compiler options to use a custom version of handlebars.js.

HandlebarsAssets::Config.compiler = 'my_handlebars.js' # Change the name of the compiler file
HandlebarsAssets::Config.compiler_path = Rails.root.join('app/assets/javascripts') # Change the location of the compiler file

Thanks

This gem is standing on the shoulders of giants.

Thank you Yehuda Katz (@wycats) for handlebars.js and lots of other code I use every day.

Thank you Charles Lowell (@cowboyd) for therubyracer and handlebars.rb.

Author

Hi, I'm Les Hill and I make things go.

Follow me on Github and Twitter.

Contributors

• Matt Burke (@spraints) : execjs support

•                (@kendagriff)  : 1.8.7 compatibility
  

• Thorben Schröder (@walski) : 3.1 asset group for precompile
• Erwan Barrier (@erwanb) : Support for plain sprockets
• Brendan Loudermilk (@bloudermilk) : HandlebarsAssets.path
• Dan Evans (@danevans) : Rails 2 support
• Ben Woosley (@empact) : Update to handlebars.js 1.0.0.beta.6

•                (@cw-moshe)    : Remove 'templates/' from names
  

• Spike Brehm (@spikebrehm) : Config.template_namespace option
• Ken Mayer (@kmayer) : Quick fix for template_namespace option
• Brad Murray (@wyaeld) : Generic options support

Contributing

Pull requests are welcome! Please do not update the version number.

In a nutshell:

1. Fork
2. Create a topic branch - git checkout -b my_branch
3. Push to your branch - git push origin my_branch
4. Create a Pull Request from your branch
5. That's it!