module ActionController #:nodoc: # Actions that fail to perform as expected throw exceptions. These exceptions can either be rescued for the public view # (with a nice user-friendly explanation) or for the developers view (with tons of debugging information). The developers view # is already implemented by the Action Controller, but the public view should be tailored to your specific application. # # The default behavior for public exceptions is to render a static html file with the name of the error code thrown. If no such # file exists, an empty response is sent with the correct status code. # # You can override what constitutes a local request by overriding the local_request? method in your own controller. # Custom rescue behavior is achieved by overriding the rescue_action_in_public and rescue_action_locally methods. module Rescue LOCALHOST = '127.0.0.1'.freeze DEFAULT_RESCUE_RESPONSE = :internal_server_error DEFAULT_RESCUE_RESPONSES = { 'ActionController::RoutingError' => :not_found, 'ActionController::UnknownAction' => :not_found, 'ActiveRecord::RecordNotFound' => :not_found, 'ActiveRecord::StaleObjectError' => :conflict, 'ActiveRecord::RecordInvalid' => :unprocessable_entity, 'ActiveRecord::RecordNotSaved' => :unprocessable_entity, 'ActionController::MethodNotAllowed' => :method_not_allowed, 'ActionController::NotImplemented' => :not_implemented, 'ActionController::InvalidToken' => :unprocessable_entity } DEFAULT_RESCUE_TEMPLATE = 'diagnostics' DEFAULT_RESCUE_TEMPLATES = { 'ActionController::MissingTemplate' => 'missing_template', 'ActionController::RoutingError' => 'routing_error', 'ActionController::UnknownAction' => 'unknown_action', 'ActionView::TemplateError' => 'template_error' } def self.included(base) #:nodoc: base.cattr_accessor :rescue_responses base.rescue_responses = Hash.new(DEFAULT_RESCUE_RESPONSE) base.rescue_responses.update DEFAULT_RESCUE_RESPONSES base.cattr_accessor :rescue_templates base.rescue_templates = Hash.new(DEFAULT_RESCUE_TEMPLATE) base.rescue_templates.update DEFAULT_RESCUE_TEMPLATES base.class_inheritable_hash :rescue_handlers base.rescue_handlers = {} base.extend(ClassMethods) base.class_eval do alias_method_chain :perform_action, :rescue end end module ClassMethods #:nodoc: def process_with_exception(request, response, exception) new.process(request, response, :rescue_action, exception) end # Rescue exceptions raised in controller actions by passing at least one exception class and a :with option that contains the name of the method to be called to respond to the exception. # Handler methods that take one argument will be called with the exception, so that the exception can be inspected when dealing with it. # # class ApplicationController < ActionController::Base # rescue_from User::NotAuthorized, :with => :deny_access # self defined exception # rescue_from ActiveRecord::RecordInvalid, :with => :show_errors # # protected # def deny_access # ... # end # # def show_errors(exception) # exception.record.new_record? ? ... # end # end def rescue_from(*klasses) options = klasses.extract_options! unless options.has_key?(:with) # allow nil raise ArgumentError, "Need a handler. Supply an options hash that has a :with key as the last argument." end klasses.each do |klass| rescue_handlers[klass.name] = options[:with] end end end protected # Exception handler called when the performance of an action raises an exception. def rescue_action(exception) log_error(exception) if logger erase_results if performed? return if rescue_action_with_handler(exception) # Let the exception alter the response if it wants. # For example, MethodNotAllowed sets the Allow header. if exception.respond_to?(:handle_response!) exception.handle_response!(response) end if consider_all_requests_local || local_request? rescue_action_locally(exception) else rescue_action_in_public(exception) end end # Overwrite to implement custom logging of errors. By default logs as fatal. def log_error(exception) #:doc: ActiveSupport::Deprecation.silence do if ActionView::TemplateError === exception logger.fatal(exception.to_s) else logger.fatal( "\n\n#{exception.class} (#{exception.message}):\n " + clean_backtrace(exception).join("\n ") + "\n\n" ) end end end # Overwrite to implement public exception handling (for requests answering false to local_request?). By # default will call render_optional_error_file. Override this method to provide more user friendly error messages.s def rescue_action_in_public(exception) #:doc: render_optional_error_file response_code_for_rescue(exception) end # Attempts to render a static error page based on the status_code thrown, # or just return headers if no such file exists. For example, if a 500 error is # being handled Rails will first attempt to render the file at public/500.html. # If the file doesn't exist, the body of the response will be left empty. def render_optional_error_file(status_code) status = interpret_status(status_code) path = "#{RAILS_ROOT}/public/#{status[0,3]}.html" if File.exists?(path) render :file => path, :status => status else head status end end # True if the request came from localhost, 127.0.0.1. Override this # method if you wish to redefine the meaning of a local request to # include remote IP addresses or other criteria. def local_request? #:doc: request.remote_addr == LOCALHOST and request.remote_ip == LOCALHOST end # Render detailed diagnostics for unhandled exceptions rescued from # a controller action. def rescue_action_locally(exception) add_variables_to_assigns @template.instance_variable_set("@exception", exception) @template.instance_variable_set("@rescues_path", File.dirname(rescues_path("stub"))) @template.send(:assign_variables_from_controller) @template.instance_variable_set("@contents", @template.render_file(template_path_for_local_rescue(exception), false)) response.content_type = Mime::HTML render_for_file(rescues_path("layout"), response_code_for_rescue(exception)) end # Tries to rescue the exception by looking up and calling a registered handler. def rescue_action_with_handler(exception) if handler = handler_for_rescue(exception) if handler.arity != 0 handler.call(exception) else handler.call end true # don't rely on the return value of the handler end end private def perform_action_with_rescue #:nodoc: perform_action_without_rescue rescue Exception => exception # errors from action performed rescue_action(exception) end def rescues_path(template_name) "#{File.dirname(__FILE__)}/templates/rescues/#{template_name}.erb" end def template_path_for_local_rescue(exception) rescues_path(rescue_templates[exception.class.name]) end def response_code_for_rescue(exception) rescue_responses[exception.class.name] end def handler_for_rescue(exception) if handler = rescue_handlers[exception.class.name] method(handler) end end def clean_backtrace(exception) if backtrace = exception.backtrace if defined?(RAILS_ROOT) backtrace.map { |line| line.sub RAILS_ROOT, '' } else backtrace end end end end end