Question

I’ve written a mixin (based on something I read in a blog) that seems to be causing a problem

Here is a link to the project: http://www.filehosting.org/file/details/263759/onlinescheduler.zip (or send me an email: [e-mail] and I’ll email it) and I’ve stripped as much out as I can for it to still cause the problem. The key files to look at are:

/lib/user_role.rb (near line 11)
/app/views/customers/index.html.erb (near line 16)
/app/controllers/customers_controller.rb (near line 47)

I’ll layout the important stuff here as well:

/lib/user_role.rb:

module UserRole
    def self.included(base)
      base.has_one :user, :as => :user_role, :autosave => true
      base.validate :user_must_be_valid
      base.alias_method_chain :user, :autobuild
      base.extend ClassMethods
      base.define_user_accessors
    end

    def user_with_autobuild
      user_without_autobuild || build_user
    end

    def method_missing(meth, *args, &blk)
      user.send(meth, *args, &blk)
    rescue NoMethodError
      super
    end

    module ClassMethods
      def define_user_accessors
        all_attributes = User.content_columns.map(&:name) + ["password", "password_confirmation"]
        ignored_attributes = ["created_at", "updated_at", "user_role_type"]
        attributes_to_delegate = all_attributes - ignored_attributes
        attributes_to_delegate.each do |attrib|
          class_eval <<-RUBY
            def #{attrib}
              user.#{attrib}
            end

            def #{attrib}=(value)
              self.user.#{attrib} = value
            end

            def #{attrib}?
              self.user.#{attrib}?
            end
          RUBY
        end
      end
    end

  protected
    def user_must_be_valid
      Logger.new(STDOUT).info('calling user_must_be_valid')
      unless user.valid?
        user.errors.each do |attr, message|
          errors.add(attr, message)
        end
      end
    end
  end

app/views/customers/index.html.erb:

...
<% @customers.each do |customer| %>
  <tr>
    <td><%= customer.account_id %></td>
...

accessing customer at all causes the problem. I can do anything to @customers
but as soon as I try to access customer.... or even @customers[0].... I get a problem.

Steps to produce

1) After unzipping the file, go into the root directory in terminal and run these commands:

bundle install
bundle exec rake db:drop
bundle exec rake db:migrate
rails s

2) Open your browser to localhost:3000/customers and click New Customer

3) Fill in the form you see like so:

Account: 3
First Name: First
Last Name: Last
Email: [e-mail]
Password: 1234
Password confirmation: 1234

4) Click the Create Customer button.

Expected Behavior

You should be redirected to localhost:3000/customers/1

Current Behaviour

The webserver crashes as you get the following message:

~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x17b356) [0x7fef4a97e356]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x1713ee) [0x7fef4a9743ee]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x177243) [0x7fef4a97a243]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(rb_vm_invoke_proc+0x9f) [0x7fef4a97b08f]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x17b644) [0x7fef4a97e644]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x1713ee) [0x7fef4a9743ee]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x177243) [0x7fef4a97a243]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x1784f4) [0x7fef4a97b4f4]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x178cb5) [0x7fef4a97bcb5]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x17b50d) [0x7fef4a97e50d]
~/.rvm/rubies/ruby-1.9.2-p290/lib/libruby.so.1.9(+0x1713ee) [0x7fef4a9743ee]

[NOTE]
You may have encountered a bug in the Ruby interpreter or extension libraries.
Bug reports are welcome.
For details: http://www.ruby-lang.org/bugreport.html

Rerunning the webserver and going to localhost:3000/customers sometimes gives you a different error. A segmentation fault and it complains about /lib/user_role.rb:11

Environment

Ruby 1.9.2-p290
Rails 3.0.9
RVM 1.8.1
Ubuntu 11.04

Edit

Something to note: If you try working the same code that bombs in console it seems fine. Example:

(After entering rails c)
@customers = Customer.all
@customers.each do |customer|
  p customer.account_id
end
# this doesn't cause an error or crash.

@customer[0].first_name
=> "First"

Answer 1

If you remove:

def method_missing(meth, *args, &blk)
  customer.send(meth, *args, &blk)
rescue NoMethodError
  super
end

and

def method_missing(meth, *args, &blk)
  user.send(meth, *args, &blk)
rescue NoMethodError
  super
end

from the x_role files in your lib directory, it should work fine. On a side note look into inherited resource for your controllers and simple form for your forms.