engine/lib/locomotive/middlewares/seo_trailing_slash.rb

module Locomotive
  module Middlewares
    class SeoTrailingSlash

      def initialize(app, opts = {})
        @app = app
      end

      def call(env)
        path = env['PATH_INFO']

        if !path.starts_with?('/admin/') && (match = path.match(%r{(.+)/$}))
          response = Rack::Response.new
          response.redirect(match[1], 301) # moved permanently
          response.finish
          response.to_a
        else
          @app.call(env)
        end
      end

    end
  end
end