how to create rails 3 custom exceptions

Question

i am creating some custom exceptions as follows

lib/exceptions.rb

module Exceptions
  class MemberOverFlow < StandardError
  end
  rescue_from MemberOverFlow do |exception|
    redirect_to root_url, :alert => exception.message
  end
end

I use to raise the exception like this.

raise Exception::MemberOverFlow"member count overflow"

It giving the following error

NoMethodError in MembersController#create

undefined method `MemberOverFlow' for Exception:Class

can anyone tell me what is problem

thanks

Answer 1

Did you require the module in the controller where you are trying to raise the exception?

require "exception" #or wherever you have placed the module file

Use:
raise Exception::MemberOverFlow.new("member count overflow")

and if it still does not work, try changing the name of the module "Exception" because Exception is an existing exception class defined in Ruby.

Answer 2

No one specifically called out what was wrong in the original post. The following:

raise Exceptions::MemberOverFlow"member count overflow"

is treating MemberOverFlow as a METHOD and not the class that it is. You need to call the new method on your MemberOverFlow class, which is what amit_saxena's answer points out.

That answer solves the problem, but I just felt it was worth pointing out what you were doing syntactically so that if you ever had a similar problem in the future you would know what was going on.

Answer 3

The contents of your lib directory are not automatically loaded in rails 3, you need to specify them like so in config/application.rb:

config.autoload_paths += %W(#{config.root}/lib)

Perhaps you have not done that?