Methods
R
Instance Public methods
rescue_from(*klasses, &block)

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

Source: show | on GitHub 

    # File activesupport/lib/active_support/rescuable.rb, line 51
51:       def rescue_from(*klasses, &block)
52:         options = klasses.extract_options!
53: 
54:         unless options.has_key?(:with)
55:           if block_given?
56:             options[:with] = block
57:           else
58:             raise ArgumentError, "Need a handler. Supply an options hash that has a :with key as the last argument."
59:           end
60:         end
61: 
62:         klasses.each do |klass|
63:           key = if klass.is_a?(Class) && klass <= Exception
64:             klass.name
65:           elsif klass.is_a?(String)
66:             klass
67:           else
68:             raise ArgumentError, "#{klass} is neither an Exception nor a String"
69:           end
70: 
71:           # put the new handler at the end because the list is read in reverse
72:           self.rescue_handlers += [[key, options[:with]]]
73:         end
74:       end