Module ActionController::Rescue
In: actionpack/lib/action_controller/rescue.rb

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.

Methods

clean_backtrace   handler_for_rescue   local_request?   log_error   render_optional_error_file   rescue_action   rescue_action_in_public   rescue_action_locally   rescue_action_with_handler   rescues_path   response_code_for_rescue   template_path_for_local_rescue  

Constants

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::InvalidAuthenticityToken' => :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'

Protected Instance methods

local_request?(

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.

[Source]

# File actionpack/lib/action_controller/rescue.rb, line 143
      def local_request? #:doc:
        request.remote_addr == LOCALHOST and request.remote_ip == LOCALHOST
      end
log_error(exception)

Overwrite to implement custom logging of errors. By default logs as fatal.

[Source]

# File actionpack/lib/action_controller/rescue.rb, line 106
      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
render_optional_error_file(status_code)

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.

[Source]

# File actionpack/lib/action_controller/rescue.rb, line 130
      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
rescue_action(exception)

Exception handler called when the performance of an action raises an exception.

[Source]

# File actionpack/lib/action_controller/rescue.rb, line 88
      def rescue_action(exception)
        log_error(exception) if logger
        erase_results if performed?

        # 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
rescue_action_in_public(exception)

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

[Source]

# File actionpack/lib/action_controller/rescue.rb, line 122
      def rescue_action_in_public(exception) #:doc:
        render_optional_error_file response_code_for_rescue(exception)
      end
rescue_action_locally(exception)

Render detailed diagnostics for unhandled exceptions rescued from a controller action.

[Source]

# File actionpack/lib/action_controller/rescue.rb, line 149
      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
rescue_action_with_handler(exception)

Tries to rescue the exception by looking up and calling a registered handler.

[Source]

# File actionpack/lib/action_controller/rescue.rb, line 162
      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 Instance methods

clean_backtrace(exception)

[Source]

# File actionpack/lib/action_controller/rescue.rb, line 200
      def clean_backtrace(exception)
        if backtrace = exception.backtrace
          if defined?(RAILS_ROOT)
            backtrace.map { |line| line.sub RAILS_ROOT, '' }
          else
            backtrace
          end
        end
      end
handler_for_rescue(exception)

[Source]

# File actionpack/lib/action_controller/rescue.rb, line 194
      def handler_for_rescue(exception)
        if handler = rescue_handlers[exception.class.name]
          method(handler)
        end
      end
rescues_path(template_name)

[Source]

# File actionpack/lib/action_controller/rescue.rb, line 182
      def rescues_path(template_name)
        "#{File.dirname(__FILE__)}/templates/rescues/#{template_name}.erb"
      end
response_code_for_rescue(exception)

[Source]

# File actionpack/lib/action_controller/rescue.rb, line 190
      def response_code_for_rescue(exception)
        rescue_responses[exception.class.name]
      end
template_path_for_local_rescue(exception)

[Source]

# File actionpack/lib/action_controller/rescue.rb, line 186
      def template_path_for_local_rescue(exception)
        rescues_path(rescue_templates[exception.class.name])
      end

[Validate]