jeremiah presenter

hotwings.rb

products = Product.by_company(current_user.company.slug).includes(:facilities, :total_stocks).distinct(:sku)
sql = "SELECT DISTINCT ON (product_id) *  FROM facility_stocks WHERE product_id IN (#{@products.pluck(:id).join(', ')}) ORDER BY product_id, created_at DESC"
facility_stocks = ActiveRecord::Base.connection.execute(sql)
facilities = Facility.all # or whatever conditions you are putting on that

# then construct a collection of stuff you want to show in the view. 
# Basic principle:  don't calculate anything in a view unless absolutely necessary
# "separation of concerns" helps you know where to look for your logic
# strictly speaking the controller is not the best place for this stuff here (it would be better 
# in a presenter class) but this is a step in the right direction
#
# Define a temporary container for the complex data using Struct

FacilityInfo = Struct.new(:facility, :pallet_quantity, :case_quantity, :item_quantity)

@facility_collection_for_view = facilities.map do |facility|
  pallet_quantity = facility_stocks.select { |h| h['facility_id' ] == facility.id}.map { |h| h['pallet_quantity'] }.sum
  case_quantity = facility_stocks.select { |h| h['facility_id' ] == facility.id}.map { |h| h['case_quantity'] }.sum
  item_quantity = facility_stocks.select { |h| h['facility_id' ] == facility.id}.map { |h| h['item_quantity'] }.sum
  FacilityInfo.new(facility: facility, pallet_quantity: pallet_quantity, case_quantity: case_quantity, item_quantity: item_quantity)
end

#in view 

<% @facility_collection_for_view.each do |facility_info| %>
    <td><%= facility_info.pallet_quantity %></td>
    <td><%= facility_info.case_quantity %></td>
    <td><%= facility_info.item_quantity %></td>
<% end %>

    # anyway, now at least when you need to reason about your data, you can do it in the ruby code and not in 
    # the html or erb.
    #
    # Basically what you want to build is a "presenter" class whenever you have a bunch of data
    # that needs all kinds of massaging to get to what you want to show.  You can build a class
    # that just has ONE job--to get at that data and build a presenter object that can be passed to a view
    # http://nithinbekal.com/posts/rails-presenters/