Create a class to populate page in ruby 1.8.7

Question

I'm trying to make a class to populate a deals tab on my website.

Part 1. Take an items close date (CatalogItem.close_date) and use all items within 12 hours of closing. Part 2. Calculate the deal percentage by using the current price (CatalogItem.current_price) and estimated value (Item.estimated_price) <-- You'll notice they're in different tables but they're identified by an identical item_id.

I'm green in RoR, so I'm having trouble connecting this in a class, but I can make it work individually in the console:

hour_diff = (CatalogItem.last.close_date - Time.now) / 1.hour
deal_percentage = (CatalogItem.last.current_price.to_f / Item.last.estimated_price)*100   

As you can see I'm using my .last piece of data, but I want to create an array that runs through all my items, that's where my knowledge goes dry, any help would be much apreciated

Answer 1

I'm assuming you are using a belongs_to, but I think what you want to do is use an instance method. This would be your model, app/models/catalog_item.rb

class CatalogItem < ActiveRecord::Base
  belongs_to :item

  def hours_remaining
    (close_date - Time.now) / 1.hour
  end

  def deal_percentage
    (current_price.to_f / item.estimated_price)*100
  end
end

Then, you could access them in a view something like this:

<table>
  <% CatalogItem.all.each do |ci| %>
    <tr>
      <td><%= ci.hours_remaining %></td>
      <td><%= ci.deal_percentage %></td>
    </tr>
  <% end %>
</table>