application_controller.rb

class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception
  before_filter :load_config

  def load_config
    @site = Siteconfig.first
  end

end

error

undefined method `theme' for nil:NilClass

Rails.root: /vagrant/blogplatform

Application Trace | Framework Trace | Full Trace
app/controllers/welcome_controller.rb:3:in `<class:WelcomeController>'
app/controllers/welcome_controller.rb:1:in `<top (required)>'

welcome_controller.rb

class WelcomeController < ApplicationController

  layout :set_theme_layout

  def index

  end
  
  def set_theme_layout
    "#{@site.theme}/layout/application"  
  end

end