application_controller.rb

class ApplicationController < ActionController::Base

  rescue_from ActiveRecord::RecordNotFound, :with => :resource_not_found

  rescue_from ActionController::RoutingError, :with => :check_request_uri_and_method

  rescue_from AbstractController::ActionNotFound, :with => :page_not_found

  rescue_from ActionController::MethodNotAllowed, :with => :method_not_allowed

  private

  def resource_not_found
    respond_to do |format|
      format.html{ render :template=>'/rescues/record_not_found', :status => 404 }
      format.xml{  render :xml => 'Record Not Found',             :status => 404 }
      format.json{ render :json => 'Record Not Found',            :status => 404 }
    end
  end

  def page_not_found
    respond_to do |format|
      format.html{ render :template=>'/rescues/page_not_found', :status => 404 }
      format.xml{  render :xml => 'Page Not Found',             :status => 404 }
      format.json{ render :json => 'Page Not Found',            :status => 404 }
    end
  end

  def method_not_allowed(exception)
    response.headers['Allow'] ||= exception.allowed_methods.map { |method_symbol| method_symbol.to_s.upcase } * ', '
    respond_to do |format|
      format.html{ render :template=>'/rescues/method_not_allowed', :status => 405 }
      format.xml{  render :xml => 'Method Not Allowed',             :status => 405 }
      format.json{ render :json => 'Method Not Allowed',            :status => 405 }
    end
  end

  def not_implmented(exception)
    response.headers['Allow'] ||= exception.allowed_methods.map { |method_symbol| method_symbol.to_s.upcase } * ', '
    respond_to do |format|
      format.html{ render :template=>'/rescues/method_not_allowed', :status => 501 }
      format.xml{  render :xml => 'Not Implemented',                :status => 501 }
      format.json{ render :json => 'Not Implemented',               :status => 501 }
    end
  end

  def check_request_uri_and_method
    method, path = env['REQUEST_METHOD'].downcase.to_sym, env['PATH_INFO']

    # Route was not recognized. Try to find out why (maybe wrong verb).
    allows = ActionDispatch::HTTP_METHODS.select do |verb|
      begin
        Rails.application.routes.recognize_path(path, {:method => verb}, false)
      rescue ActionController::RoutingError
        nil
      end
    end

    if !ActionDispatch::HTTP_METHODS.include?(method)
      method_not_allowed ActionController::NotImplemented.new(*allows)
    elsif !allows.empty?
      method_not_allowed ActionController::MethodNotAllowed.new(*allows)
    else
      page_not_found
    end
  end
end