Mustache

Inspired by ctemplate and et, Mustache is a framework-agnostic way to render logic-free views.

As ctemplates says, "It emphasizes separating logic from presentation: it is impossible to embed application logic in this template language."

For a list of implementations (other than Ruby) and tips, see http://mustache.github.io/.

Overview

Think of Mustache as a replacement for your views. Instead of views consisting of ERB or HAML with random helpers and arbitrary logic, your views are broken into two parts: a Ruby class and an HTML template.

We call the Ruby class the "view" and the HTML template the "template."

All your logic, decisions, and code is contained in your view. All your markup is contained in your template. The template does nothing but reference methods in your view.

This strict separation makes it easier to write clean templates, easier to test your views, and more fun to work on your app's front end.

Why?

I like writing Ruby. I like writing HTML. I like writing JavaScript.

I don't like writing ERB, Haml, Liquid, Django Templates, putting Ruby in my HTML, or putting JavaScript in my HTML.

Installation

Install the gem locally with:

$ gem install mustache

Or add it to your Gemfile:

gem "mustache", "~> 1.0"

Usage

Quick example:

>> require 'mustache'
=> true
>> Mustache.render("Hello {{planet}}", planet: "World!")
=> "Hello World!"

We've got an examples folder but here's the canonical one:

class Simple < Mustache
  def name
    "Chris"
  end

  def value
    10_000
  end

  def taxed_value
    value * 0.6
  end

  def in_ca
    true
  end
end

We simply create a normal Ruby class and define methods. Some methods reference others, some return values, some return only booleans.

Now let's write the template:

Hello {{name}}
You have just won {{value}} dollars!
{{#in_ca}}
Well, {{taxed_value}} dollars, after taxes.
{{/in_ca}}

This template references our view methods. To bring it all together, here's the code to render actual HTML;

Simple.render

Which returns the following:

Hello Chris
You have just won 10000 dollars!
Well, 6000.0 dollars, after taxes.

Simple.

Tag Types

For a language-agnostic overview of Mustache's template syntax, see the mustache(5) manpage or http://mustache.github.io/mustache.5.html.

Escaping

Mustache does escape all values when using the standard double Mustache syntax. Characters which will be escaped: & \ " < > (as well as ' in Ruby >= 2.0). To disable escaping, simply use triple mustaches like {{{unescaped_variable}}}.

Example: Using {{variable}} inside a template for 5 > 2 will result in 5 > 2, where as the usage of {{{variable}}} will result in 5 > 2.

Dict-Style Views

ctemplate and friends want you to hand a dictionary to the template processor. Mustache supports a similar concept. Feel free to mix the class-based and this more procedural style at your leisure.

Given this template (winner.mustache):

Hello {{name}}
You have just won {{value}} bucks!

We can fill in the values at will:

view = Winner.new
view[:name] = 'George'
view[:value] = 100
view.render

Which returns:

Hello George
You have just won 100 bucks!

We can re-use the same object, too:

view[:name] = 'Tony'
view.render # => Hello Tony\nYou have just won 100 bucks!

Templates

A word on templates. By default, a view will try to find its template on disk by searching for an HTML file in the current directory that follows the classic Ruby naming convention.

TemplatePartial => ./template_partial.mustache

You can set the search path using Mustache.template_path. It can be set on a class by class basis:

class Simple < Mustache
  self.template_path = __dir__
end

Now Simple will look for simple.mustache in the directory it resides in, no matter the cwd.

If you want to just change what template is used you can set Mustache.template_file directly:

Simple.template_file = './blah.mustache'

Mustache also allows you to define the extension it'll use.

Simple.template_extension = 'xml'

Given all other defaults, the above line will cause Mustache to look for './blah.xml'

Feel free to set the template directly:

Simple.template = 'Hi {{person}}!'

Or set a different template for a single instance:

Simple.new.template = 'Hi {{person}}!'

Whatever works.

Views

Mustache supports a bit of magic when it comes to views. If you're authoring a plugin or extension for a web framework (Sinatra, Rails, etc), check out the view_namespace and view_path settings on the Mustache class. They will surely provide needed assistance.

Helpers

What about global helpers? Maybe you have a nifty gravatar function you want to use in all your views? No problem.

This is just Ruby, after all.

module ViewHelpers
  def gravatar
    gravatar_id = Digest::MD5.hexdigest(self[:email].to_s.strip.downcase)
    gravatar_for_id(gravatar_id)
  end

  def gravatar_for_id(gid, size = 30)
    "#{gravatar_host}/avatar/#{gid}?s=#{size}"
  end

  def gravatar_host
    @ssl ? 'https://secure.gravatar.com' : 'http://www.gravatar.com'
  end
end

Then just include it:

class Simple < Mustache
  include ViewHelpers

  def name
    "Chris"
  end

  def value
    10_000
  end

  def taxed_value
    value * 0.6
  end

  def in_ca
    true
  end

  def users
    User.all
  end
end

Great, but what about that @ssl ivar in gravatar_host? There are many ways we can go about setting it.

Here's an example which illustrates a key feature of Mustache: you are free to use the initialize method just as you would in any normal class.

class Simple < Mustache
  include ViewHelpers

  def initialize(ssl = false)
    @ssl = ssl
  end
end

Now:

Simple.new(request.ssl?).render

Finally, our template might look like this:

<ul>
  {{# users}}
    <li><img src="{{ gravatar }}"> {{ login }}</li>
  {{/ users}}
</ul>

Integrations

Sinatra

Sinatra integration is available with the mustache-sinatra gem.

An example Sinatra application is also provided: https://github.com/defunkt/mustache-sinatra-example

If you are upgrading to Sinatra 1.0 and Mustache 0.9.0+ from Mustache 0.7.0 or lower, the settings have changed. But not that much.

See this diff for what you need to do. Basically, things are named properly now and all should be contained in a hash set using set :mustache, hash.

Rack::Bug

Mustache also provides a Rack::Bug panel. First you have to install the rack-bug-mustache_panel gem, then in your config.ru add the following code:

require 'rack/bug/panels/mustache_panel'
use Rack::Bug::MustachePanel

Using Rails? Add this to your initializer or environment file:

require 'rack/bug/panels/mustache_panel'
config.middleware.use "Rack::Bug::MustachePanel"

Vim

vim-mustache-handlebars is available at mustache/vim-mustache-handlebars

Emacs

mustache-mode.el is available at mustache/emacs

TextMate

Mustache.tmbundle

See https://gist.github.com/defunkt/323624 for installation instructions.

Command Line

See mustache(1) man page or http://mustache.github.io/mustache.1.html for command line docs.

Acknowledgements

Thanks to Tom Preston-Werner for showing me ctemplate and Leah Culver for the name "Mustache."

Special thanks to Magnus Holm for all his awesome work on Mustache's parser.

Contributing

Once you've made your great commits:

Fork Mustache
Create a topic branch - git checkout -b my_branch
Push to your branch - git push origin my_branch
Create an Issue with a link to your branch
That's it!

Mailing List

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The archive can be found at http://librelist.com/browser/mustache/.~~

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