rescue_from

Registers exception classes with a handler to be called by rescue_with_handler.

rescue_from receives a series of exception classes or class names, and an exception handler specified by a trailing :with option containing the name of a method or a Proc object. Alternatively, a block can be given as the handler.

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
  rescue_from ActiveRecord::RecordInvalid, with: :show_record_errors

  rescue_from "MyApp::BaseError" do |exception|
    redirect_to root_url, alert: exception.message
  end

  private
    def deny_access
      head :forbidden
    end

    def show_record_errors(exception)
      redirect_back_or_to root_url, alert: exception.record.errors.full_messages.to_sentence
    end
end

Exceptions raised inside exception handlers are not propagated up.