Association problem in Rails

I am new to rubies on rails. So I think I am having association problems.

Considering three classes of models with their associations:

# user.rb
class User < ActiveRecord::Base
  has_many :product_groups
  has_many :products, :through=>:product_groups
end

# product_group.rb
class ProductGroup < ActiveRecord::Base
  has_many :products
  belongs_to :user
end

# product.rb
class Product < ActiveRecord::Base
  belongs_to :product_group
  has_one :user
end

      

        
        
        
      

    

So when I try to add a new product. I am getting errors.

# products_controller.rb
  def new
    @product = current_user.product_groups.products.build
  end

      

        
        
        
      

    

I am getting the following errors:

   NoMethodError (undefined method `products' for #<Class:0x2ca50b0>):
     app/controllers/products_controller.rb:27:in `new'
     -e:2:in `load'
     -e:2

      

        
        
        
      

    

I'm confused, can someone help me? Or any other idea?