Flowdock
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

Exceptions raised inside exception handlers are not propagated up.

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April 21, 2014 - (>= v4.0.2)
0 thanks
April 9, 2009
11 thanks

Define handlers in order of most generic to most specific

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”.

July 12, 2012
1 thank

conditional rescue_from

Would it be possible to do something like:

rescue_from Exception, :with => my_handler, :unless => request.local?
February 14, 2013 - (>= v3.2.8)
1 thank

conditional rescue from does not seem working on Rails 3.2.11

Be careful, conditional rescue_from does not work in Rails 3.2.11