Precompile handlebars templates with rake-pipeline

Assetfile.rb

input "app"  do


  match "templates/**/*.handlebars" do
	filter HandlebarsPrecompiler
	filter ConcatFilter, "apptmp.js"
    	filter AddMicroLoader, :global => true
    	filter AddHandlebarsDependencies
  end
  
  .....
  
  match "vendor/handlebars.runtime-1.0.rc.2.js" do
	filter ConcatFilter, "apptmp.js"
  end

  
end

HandlebarsPrecompiler.rb

  class AddHandlebarsDependencies < Rake::Pipeline::Filter

    def generate_output(inputs, output)

        contents = <<END
 minispade.require('rsvp');
 minispade.require('container');
 minispade.require('ember-debug');
 minispade.require('ember-metal');
 minispade.require('ember-runtime');
 minispade.require('ember-application');
 minispade.require('ember-views');
 minispade.require('ember-states');
 minispade.require('metamorph');
 minispade.require('ember-handlebars');
END

      output.write contents

      inputs.each do |input|
        output.write input.read
      end

    end

end


class HandlebarsPrecompiler < Rake::Pipeline::Filter
  class << self
    def context

      unless @context

        contents = <<END

#{File.read("./app/submodules/ember.js/packages/handlebars/lib/main.js")}
#{File.read("./app/vendor/precompile/ember-runtime.js")}
#{File.read("./app/submodules/ember.js/packages/ember-handlebars-compiler/lib/main.js")}
function precompileEmberHandlebars(string) {
  return Ember.Handlebars.precompile(string).toString();
}
END

        @context = ExecJS.compile(contents)

      end
      @context
    end

  end

  def precompile_templates(name, data)
   "\nEmber.TEMPLATES['#{name}'] = Ember.Handlebars.template(#{self.class.context.call("precompileEmberHandlebars", data)});\n"
  end

  def generate_output(inputs, output)

    inputs.each do |input|

      name = File.basename(input.path, '.handlebars')
      data = File.read(input.fullpath)
      result = precompile_templates(name, data)
      output.write result

    end
  end
end

view.js

Em.View.extend({
  elementId: 'about_screen',
  templateName: 'about_screen'
});

/// use the file -> about_screen.handlebars

My project directory is something like:

app

lib
submodules

ember.js
data
...

vendor

precompile/.. ( libraries required to precompile templates )

To precompile handlebars template in the server side, some steps where necessary:

• Building an ember-runtime version to be used in the HandlebarsPrecompiler filter.
• Add the require dependencies of the precompile templates before their content appending the AddHandlebarsDependencies filter.

Any other recommend way?