Initial implementation (FLAWED)

_billable.html.haml

%tr
  %td= link_to "Details", billable
  %td= h billable.client.name
  %td= h billable.booking.date.to_s(:short)
  %td= h billable.agency.name
  %td= h billable.job_type.name
  %td= h truncate(billable.vendor.name)
  %td= h truncate(billable.project.name)
  %td= number_to_currency billable.base_rate
  %td= number_to_currency billable.gross_rate
  %td= number_to_currency billable.commission_rate
  %td= number_to_currency billable.outstanding

search.rb

class Search
  def initialize(query)
    @query = query
  end

  def billables
    # Billable.search parses the query and returns a named_scope with corresponding conditions
    @billables ||= Billable.search(@query)
  end

  def sum(column)
    billables.sum(column)
  end

  def needs_gross_invoice?
    billables.any? { |b| b.needs_gross_invoice? }
  end

  def needs_commission_invoice?
    billables.any? { |b| b.needs_commission_invoice? }
  end
end

searches_controller.rb

class SearchesController < ActionController::Base
  # GET /search[?page=#]
  def show
    @search = session[:search]
    @billables = @search.billables.paginate(:page => params[:page])
  end

  # POST /search
  def create
    session[:search] = Search.new(params[:query])
    redirect_to search_path
  end
end

show.html.haml

= link_to_if @search.needs_gross_invoice?, new_search_gross_invoice_path
|
= link_to_if @search.needs_commission_invoice?, new_search_commission_invoice_path

%table
  %thead
    / ...
  %tfoot
    %tr
      %td{:colspan => ...} Totals
      %td= number_to_currency @search.sum(:base_rate)
      %td= number_to_currency @search.sum(:gross_rate)
      %td= number_to_currency @search.sum(:commission_rate)
      %td= number_to_currency @search.sum(:outstanding)
  %tbody
    = render @billables

= will_paginate @billables