method

rescue_from

v3.2.13 - Show latest stable - Class: ActiveSupport::Rescuable::ClassMethods

rescue_from(*klasses, &block)

public

Rescue exceptions raised in controller actions.

rescue_from receives a series of exception classes or class names, and a trailing :with option with the name of a method or a Proc object to be called to handle them. Alternatively a block can be given.

Handlers that take one argument will be called with the exception, so that the exception can be inspected when dealing with it.

Handlers are inherited. They are searched from right to left, from bottom to top, and up the hierarchy. The handler of the first class for which exception.is_a?(klass) holds true is the one invoked, if any.

class ApplicationController < ActionController::Base
  rescue_from User::NotAuthorized, :with => :deny_access # self defined exception
  rescue_from ActiveRecord::RecordInvalid, :with => :show_errors

  rescue_from 'MyAppError::Base' do |exception|
    render :xml => exception, :status => 500
  end

  protected
    def deny_access
      ...
    end

    def show_errors(exception)
      exception.record.new_record? ? ...
    end
end

# File activesupport/lib/active_support/rescuable.rb, line 51
      def rescue_from(*klasses, &block)
        options = klasses.extract_options!

        unless options.has_key?(:with)
          if block_given?
            options[:with] = block
          else
            raise ArgumentError, "Need a handler. Supply an options hash that has a :with key as the last argument."
          end
        end

        klasses.each do |klass|
          key = if klass.is_a?(Class) && klass <= Exception
            klass.name
          elsif klass.is_a?(String)
            klass
          else
            raise ArgumentError, "#{klass} is neither an Exception nor a String"
          end

          # put the new handler at the end because the list is read in reverse
          self.rescue_handlers += [[key, options[:with]]]
        end
      end

3Notes

Define handlers in order of most generic to most specific

tadman · Apr 9, 200911 thanks

The later the definition of the rescue handler, the higher the priority:

rescue_from Exception, :with => :error_generic
rescue_from Exception::ComputerOnFire, :with => :panic

Declaring the Exception catch-all handler last would have the side-effect of precluding any other handlers from running.

This is what is meant by being "searched...from bottom to top".

conditional rescue_from

benissimo · Jul 12, 20121 thank

Would it be possible to do something like: rescue_from Exception, :with => my_handler, :unless => request.local?

conditional rescue from does not seem working on Rails 3.2.11

sebthemonster · Feb 14, 20131 thank

Be careful, conditional rescue_from does not work in Rails 3.2.11

rescue_from

3Notes

Define handlers in order of most generic to most specific

conditional rescue_from

conditional rescue from does not seem working on Rails 3.2.11

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