Quicker routing helpers for Rails apps

quick_routes.rb

# I hate the fact that Rails.application.routes.url_helpers.whatever
# is so damn slow.
#
# def tt n
#   start = Time.now
#   n.times { yield }
#   Time.now - start
# end
#
# tt(100) { Rails.application.routes.url_helpers.entry_path(edition_id: 'us', id: 12345) }
# => 0.192188
#
# test = (class X; include QuickRoutes; end).new
# tt(100) { test.entry_path(edition_id: 'us', id: 12345) }
# => 0.001878
#
# This isn't needless optimization. Using Rails's native helpers to
# generate links for 100 entries takes at least 100ms even on a box
# faster than my laptop.

module QuickRoutes

  @@routes = {}

  Rails.application.routes.named_routes.names.each do |sym|
    define_method("#{sym}_path") do |params={}|
      template = @@routes[sym] ||= get_route_template(sym)
      fill_route(template, params)
    end
  end

  def fill_route(template, params)
    _params = params.dup

    format = _params.delete(:format)
    template = template.sub('(.:format)', format ? ".#{format}" : '')

    missing = []
    # This is probably not a comprehensive gsubbing solution, particularly
    # if there are optional params other than format.
    base = template.gsub(/:([^:\/.]+)/) do |m|
      _params.delete($1.to_sym) { missing << $1 }
    end
    if missing.length > 0
      raise "Missing path params: #{missing.join(', ')}"
    end

    if _params.count > 0
      base + "?" + URI.encode_www_form(_params)
    else
      base
    end
  end

  def get_route_template(symbol)
    route_name = symbol.to_s
    route = Rails.application.routes.routes.find { |r| r.name == route_name }
    if route
      # If this breaks at any point, consult
      #   rails/actionpack/lib/action_dispatch/routing/inspector.rb
      # which is the formatter used to print routes to the console in the
      # rake command
      route.path.spec.to_s
    else
      raise "No such route: #{route_name}"
    end
  end

end