Question

My goal is to generate a directory of static html, javascript, and image files within my Rails (3) app, driven by ERB templates. For example, as a developer I might want to generate/update these files:

#{Rails.root}/public/products/baseball.html
#{Rails.root}/public/products/football.js

..from the following template files:

#{Rails.root}/product_templates/baseball.html.erb
#{Rails.root}/product_templates/football.js.erb

Ideally the templates would have access to my app’s Rails environment (including URL helpers, view helpers, partials, etc.).

What’s the latest and greatest way to accomplish this?

I experimented with a custom Rails generator, but found that I needed to write custom logic for skipping non-ERB files, substituting file names, etc. There must be a better way.

Answer 1

This is how I accomplished something similar. It accepts source and destination directories, wipes out the destination, then processes the source directory, either ERB-processing files and placing them in the destination or simply copying them (in the case of on-ERB files). It would need to be modified to handle recursively processing a directory.

I invoke it from a rake task like so:

DirectoryGenerator.new.generate(Rails.root.join('src'), Rails.root.join('public', 'dest'))


class DirectoryGenerator
  include Rails.application.routes.url_helpers
  include ActionView::Helpers::TagHelper
  default_url_options[:host] = 'www.example.com'

  def generate(source, destination)
    FileUtils.rmtree(destination)
    FileUtils.mkdir_p(destination)

    Dir.glob(File.join(source, '*')).each do |path|
      pathname = Pathname.new(path)
      if pathname.extname == '.erb'
        File.open(destination.join(pathname.basename.sub(/\.erb$/, '')), 'w') do |file|
          file.puts(ERB.new(File.read(path)).result(binding))
        end
      else
        FileUtils.cp(pathname, File.join(destination, pathname.basename))
      end
    end
  end
end