I am following the guide at <http://guides.rubyonrails.org/association_basics.html>
and I have created 

```
class Customer < ActiveRecord::Base
  has_many :orders, :dependent => :destroy
end

class Order < ActiveRecord::Base
  belongs_to :customer
end

```

but executing `@order = @customer.orders.create()` results in 

> 
> unknown attribute: customer\_id
> 
> 
> 

Do you know why does this error occurs? And more importantly Is there a hidden reason for all the guides for has\_many to drive you insane with showing this example, but non of them to be actually working :)