Calling a model "Update" leads to unexpected behavior

Confirmed on Rails edge:

$ script/rails g model update 
...
$ script/rails g model comment update:references body:string
...
$ rake db:migrate
...

Models:

class Update < ActiveRecord::Base
  has_many :comments
end

class Comment < ActiveRecord::Base
  belongs_to :update
end

$ script/rails c
Loading development environment (Rails 3.1.0.beta)
ruby-1.9.2-p0 > u = Update.create
 => #<Update id: 1, created_at: "2010-10-10 15:21:19", updated_at: "2010-10-10 15:21:19"> 
ruby-1.9.2-p0 > u.comments << Comment.new(:body => 'Foo.')
 => [#<Comment id: 1, update_id: 1, body: "Foo.", created_at: "2010-10-10 15:21:38", updated_at: "2010-10-10 15:21:38">] 
ruby-1.9.2-p0 > Comment.first.update_attribute(:body, 'Bar.')
 => true 
ruby-1.9.2-p0 > Comment.first
 => #<Comment id: 1, update_id: 1, body: "Foo.", created_at: "2010-10-10 15:21:38", updated_at: "2010-10-10 15:21:38">

Please provide a patch (https://rails.lighthouseapp.com/projects/8994/sending-patches) with a fix and/or a failing test.

It's not very surprising that your use case doesn't work: #update is a reserved word in ActiveRecord (it's not in the public API, but still documented).
In fact, it was already forbidden for regular attributes and methods, but not enforced for associations:

script/rails g model comment update:string

class Comment < ActiveRecord::Base
end

$ rails c
ruby-1.9.2-p0 > Comment.new(:body => 'test', :update => 'test')
ActiveRecord::DangerousAttributeError: update is defined by ActiveRecord

With the attached patch you will get the same exception in your use case, too.

Note that both in your original scenario and after my patch, you can work around this issue by naming your association differently:

class Comment < ActiveRecord::Base
  belongs_to :an_update, :class_name => Update
end

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This issue has been automatically marked as stale because it has not been commented on for at least three months.

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