Suddenly my admin pages won't load in Padrino (Template Engine not found)

I've never had an issues with the admin pages in my app before, but after a reboot of my machine I'm getting this error:

RuntimeError at /admin/sessions/new
Template engine not found: /sessions/new

With this abbreviated backtrace:

/Users/jeremysmith/code/robusto_server/admin/controllers/sessions.rb in block (2 levels) in <top (required)>
    render "/sessions/new", nil, :layout => false
/Users/jeremysmith/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/webrick/httpserver.rb in service
      si.service(req, res)

Everything in app.rb is the same as it was when this used to work:

set :login_page, "/admin/sessions/new"

  enable  :sessions
  disable :store_locatio开发者_运维问答n

  access_control.roles_for :any do |role|
    role.protect "/"
    role.allow "/sessions"
  end

  access_control.roles_for :admin do |role|
    role.project_module :stat_definitions, "/stat_definitions"
    role.project_module :accounts, "/accounts"
  end

You need to add in your app.rb

register Padrino::Rendering

I ran into this same issue using modular Sinatra pattern application and slim for my templating engine. I couldn't render templates or partials. Here is how I fixed it:

# Gemfile
gem 'padrino-core'
gem 'padrino-helpers'

# app.rb
require 'padrino-core/application/rendering'
require 'padrino-helpers'

class App < Sinatra::Base
  register Padrino::Rendering
  register Padrino::Helpers
end

more information at http://www.padrinorb.com/guides/standalone-usage-in-sinatra