CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-3join
dennismonsewicz
dennismonsewicz

Reputation: 25542

Rails 3: Join Table with additional attributes

I have a simple cart system that I have been working on for a little while for an application and am needing a little help in trying to figure out how to update a particular attribute in a join table (Between Order and Products).

Here is the code:

def add_product_to_cart
        @product = Product.by_client(current_client).first 
        @order = current_order
        unless @order.products.exists? :id => @product.id
            @order.products << @product
        end
    end

I am trying to update a particular attribute when I update the @order.products...

This is what I am trying to do: @order.products << @product --> When this happens I need to update a :price attribute..

Anyway of doing this?

Upvotes: 1

Views: 297

Answers (2)

Serge Balyuk
Serge Balyuk

Reputation: 3462

Desire to put attributes into join table may be a sign of missing model. You can promote join table into model, say OrderItem, by adding primary key to it. HABTM associations in Order and Product then become has_many through associations. The new model would be a good place for setting up callback which populates price attribute. It can also unlock additional benefits, like time-stamping items and making them act_as_list, etc.

Upvotes: 1

Caleb Hearth
Caleb Hearth

Reputation: 3365

class Order
  has_many :products
  def price
    products.sum(:price)
  end
end

Just off the top of my head. Here's the sum reference:

http://ar.rubyonrails.org/classes/ActiveRecord/Calculations/ClassMethods.html#M000296

Upvotes: 1

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