Scope question

StorageFee.rb

class StorageFee < ActiveRecord::Base
  OVERSTOCK_CHARGE_PER_ITEM = 0.02  # [TO20120202@0909] This is how much we charge/overstocked item.
  belongs_to :publisher

  # TODO[TO20120205@1954] Duplication with invoice, invoice_upload, sales_item
  cattr_reader :per_page
  @@per_page = 20

  scope :by_publisher_id, lambda { |id| where(:publisher_id => id) }
  scope :to_date_on, lambda { |date| where(:to_date => date) }
  scope :fee_summary, select("date(to_date) AS ordered_date, sum(overstock * 0.02) AS total_fees, sum(onhand) AS total_onhand, sum(overstock) AS total_overstock").group("date(to_date)")

### What do I have to do to this scope to hydrate the publisher?  Or just JOIN in the publisher table?
  scope :publisher_fee_summary, select("publisher_id, sum(soldqty) as total_sold, sum(overstock * 0.02) AS total_fees, sum(onhand) AS total_onhand, sum(overstock) AS total_overstock").group("publisher_id")


  scope :ordered, order("storage_fees.to_date DESC")
  scope :short_term, where("overstock > 0")
  def total_fee
    return 0.00 if (self.overstock.nil? || self.overstock < 0)
    (OVERSTOCK_CHARGE_PER_ITEM * self.overstock).round(2)
  end

  comma do
    to_date "Date"
    publisher :abbrev => 'Publisher'
    isbn13 "ISBN-13"
    isbn10 "ISBN-10"
    title "Title"
    soldqty "Sold"
    onhand "On Hand"
    overstock "Overstock"
    total_fee "Total Fee"
  end
end

I would suggest you use

scope :publisher_fee_summary, includes(:publisher).select("publisher_id, sum(soldqty) as total_sold, sum(overstock * 0.02) AS total_fees, sum(onhand) AS total_onhand, sum(overstock) AS total_overstock").group("publisher_id")

Note the includes in there which loads in the publisher model. You can also you join() but it introduces more SQL into this scope with I'd rather avoid if possible.

Here are the details in the Rails guide:

http://guides.rubyonrails.org/active_record_querying.html#eager-loading-associations