title: Rails 3 NoMethodError undefined method `name'
body: <p>When I call comment.save on a comment object i get an error, any help debugging this? </p>
  
  <p>Here is the output:</p>
  
  <pre><code>NoMethodError: undefined method `name' for #&lt;Comment:0x107b4c280&gt;
      from /Library/Ruby/Gems/1.8/gems/activemodel-3.0.5/lib/active_model/attribute_methods.rb:364:in `method_missing'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/attribute_methods.rb:46:in `method_missing'
      from /Library/Ruby/Gems/1.8/gems/activemodel-3.0.5/lib/active_model/errors.rb:224:in `read_attribute_for_validation'
      from /Library/Ruby/Gems/1.8/gems/activemodel-3.0.5/lib/active_model/errors.rb:224:in `send'
      from /Library/Ruby/Gems/1.8/gems/activemodel-3.0.5/lib/active_model/errors.rb:224:in `add_on_blank'
      from /Library/Ruby/Gems/1.8/gems/activemodel-3.0.5/lib/active_model/errors.rb:223:in `each'
      from /Library/Ruby/Gems/1.8/gems/activemodel-3.0.5/lib/active_model/errors.rb:223:in `add_on_blank'
      from /Library/Ruby/Gems/1.8/gems/activemodel-3.0.5/lib/active_model/validations/presence.rb:9:in `validate'
      from /Library/Ruby/Gems/1.8/gems/activesupport-3.0.5/lib/active_support/callbacks.rb:314:in `send'
      from /Library/Ruby/Gems/1.8/gems/activesupport-3.0.5/lib/active_support/callbacks.rb:314:in `_callback_before_1143'
      from /Library/Ruby/Gems/1.8/gems/activesupport-3.0.5/lib/active_support/callbacks.rb:414:in `_run_validate_callbacks'
      from /Library/Ruby/Gems/1.8/gems/activemodel-3.0.5/lib/active_model/validations.rb:212:in `run_validations!'
      from /Library/Ruby/Gems/1.8/gems/activemodel-3.0.5/lib/active_model/validations/callbacks.rb:67:in `run_validations!'
      from /Library/Ruby/Gems/1.8/gems/activesupport-3.0.5/lib/active_support/callbacks.rb:413:in `_run_validation_callbacks'
      from /Library/Ruby/Gems/1.8/gems/activemodel-3.0.5/lib/active_model/validations/callbacks.rb:67:in `run_validations!'
      from /Library/Ruby/Gems/1.8/gems/activemodel-3.0.5/lib/active_model/validations.rb:179:in `valid?'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/validations.rb:55:in `valid?'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/validations.rb:75:in `perform_validations'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/validations.rb:43:in `save'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/attribute_methods/dirty.rb:21:in `save'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/transactions.rb:240:in `save'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/transactions.rb:292:in `with_transaction_returning_status'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/connection_adapters/abstract/database_statements.rb:139:in `transaction'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/transactions.rb:207:in `transaction'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/transactions.rb:290:in `with_transaction_returning_status'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/transactions.rb:240:in `save'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/transactions.rb:251:in `rollback_active_record_state!'
      from /Library/Ruby/Gems/1.8/gems/activerecord-3.0.5/lib/active_record/transactions.rb:239:in `save'
      from (irb):645
      from :0&gt;&gt; 
  </code></pre>
  
  <p>...</p>
  
  <p>this happens after running: </p>
  
  <pre><code>c = event.comment.new
  c.body = "test comment"
  c.save
  </code></pre>
  
  <p>I've read a lot of threads saying that this is an issue with Rails version and Rubygems version but I find that hard to believe. </p>