Ruby on Rails: Equating items in controllers (or maybe models?)

Question

I'm trying to make attributes equal predetermined values, and I'm not sure if I'm doing that efficiently with the following (in my orders controller):

def create
  @order = Order.find(params[:id])
  @order.price = 5.99
  @order.representative = Product.find(params[:product_id]).representative
  @order.shipping_location = SHIPPING_LOCATION
  @order.user = current_user

  respond_to do |format|
   ...
  end
end

Is there a more efficient way to equate attributes in Rails (maybe using models)? If I'm using two different controllers, do I just repeat what I did above for the new controller?

Answer 1

Use before_create callback in model to assign default values.

Answer 2

Your code is a little off, it looks like a controller action for create, but the code reads like it's for an update.

Regardless... You could use a parameter hash to update everything at once.

In the case where you're creating:

order_update = {:price => 5.99, :representative => 
  Product.find(params[:product_id]).representative, 
  :shipping_location => SHIPPING_LOCATION,
  :user => current_user}

@order = Order.new(order_update)

In the case where you're updating:

@order.update_attributes(order_update) #attempts to save.

Mixing it into your controller code we get:

def create
  @order = Order.find(params[:id])
  order_update = {:price => 5.99, :representative => 
    Product.find(params[:product_id]).representative, 
    :shipping_location => SHIPPING_LOCATION,
    :user => current_user}    

  respond_to do |format|
    if @order.update_attributes(order_update)
      # save succeeded. Redirect.
    else
      # save failed. Render with errors. 
    end
  end
end

Answer 3

Another solution:

class Example < ActiveRecord::Base
  DEFAULTS = HashWithIndifferentAccess.new(:some => 'default', :values => 'here')

  def initialize(params = {})
    super(DEFAULTS.merge(params))
  end
end

Either use initialize and merge with params, or use an ActiveRecord hook like before_create etc.