Extract Budget Investment to_csv to its own class

The csv generation doesn't seem like a Model concern, at least not taking
into account the amount of lines of the method (36+). Just a simple ruby
class that encapsulates the logic makes it easier to read and maintain as
we increase the columns exported.. also customize in case other forks need
different values.

app/controllers/admin/budget_investments_controller.rb

@@ -20,7 +20,7 @@ class Admin::BudgetInvestmentsController < Admin::BaseController
       format.html
       format.js
       format.csv do
-        send_data Budget::Investment.to_csv(@investments),
+        send_data Budget::Investment::Exporter.new(@investments).to_csv,
                   filename: 'budget_investments.csv'
       end
     end

app/models/budget/investment.rb

@@ -1,5 +1,3 @@
-require 'csv'
-
 class Budget
   class Investment < ActiveRecord::Base
     SORTING_OPTIONS = %w(id title supports).freeze
@@ -328,49 +326,6 @@ class Budget
       self.valuator_groups.collect(&:name).compact.join(', ').presence
     end
 
-    def self.to_csv(investments)
-      attrs = [I18n.t("admin.budget_investments.index.table_id"),
-               I18n.t("admin.budget_investments.index.table_title"),
-               I18n.t("admin.budget_investments.index.table_supports"),
-               I18n.t("admin.budget_investments.index.table_admin"),
-               I18n.t("admin.budget_investments.index.table_valuator"),
-               I18n.t("admin.budget_investments.index.table_valuation_group"),
-               I18n.t("admin.budget_investments.index.table_geozone"),
-               I18n.t("admin.budget_investments.index.table_feasibility"),
-               I18n.t("admin.budget_investments.index.table_valuation_finished"),
-               I18n.t("admin.budget_investments.index.table_selection")]
-      csv_string = CSV.generate(headers: true) do |csv|
-        csv << attrs
-        investments.each do |investment|
-          id = investment.id.to_s
-          title = investment.title
-          total_votes = investment.total_votes.to_s
-          admin = if investment.administrator.present?
-                    investment.administrator.name
-                  else
-                    I18n.t("admin.budget_investments.index.no_admin_assigned")
-                  end
-          assigned_valuators = investment.assigned_valuators || '-'
-          assigned_valuation_groups = investment.assigned_valuation_groups || '-'
-          vals = if investment.valuators.empty?
-                   I18n.t("admin.budget_investments.index.no_valuators_assigned")
-                 else
-                   investment.valuators.collect(&:description_or_name).join(', ')
-                 end
-          heading_name = investment.heading.name
-          price_string = "admin.budget_investments.index.feasibility"\
-                         ".#{investment.feasibility}"
-          price = I18n.t(price_string, price: investment.formatted_price)
-          valuation_finished = investment.valuation_finished? ?
-                                         I18n.t('shared.yes') :
-                                         I18n.t('shared.no')
-          csv << [id, title, total_votes, admin, assigned_valuators, assigned_valuation_groups,
-                  heading_name, price, valuation_finished]
-        end
-      end
-      csv_string
-    end
-
     private
 
       def set_denormalized_ids

app/models/budget/investment/exporter.rb

@@ -0,0 +1,59 @@
+class Budget::Investment::Exporter
+  require 'csv'
+
+  def initialize(investments)
+    @investments = investments
+  end
+
+  def to_csv
+    CSV.generate(headers: true) do |csv|
+      csv << headers
+      @investments.each { |investment| csv << csv_values(investment) }
+    end
+  end
+
+  private
+
+  def headers
+    [
+      I18n.t("admin.budget_investments.index.table_id"),
+      I18n.t("admin.budget_investments.index.table_title"),
+      I18n.t("admin.budget_investments.index.table_supports"),
+      I18n.t("admin.budget_investments.index.table_admin"),
+      I18n.t("admin.budget_investments.index.table_valuator"),
+      I18n.t("admin.budget_investments.index.table_valuation_group"),
+      I18n.t("admin.budget_investments.index.table_geozone"),
+      I18n.t("admin.budget_investments.index.table_feasibility"),
+      I18n.t("admin.budget_investments.index.table_valuation_finished"),
+      I18n.t("admin.budget_investments.index.table_selection")
+    ]
+  end
+
+  def csv_values(investment)
+    [
+      investment.id.to_s,
+      investment.title,
+      investment.total_votes.to_s,
+      admin(investment),
+      investment.assigned_valuators || '-',
+      investment.assigned_valuation_groups || '-',
+      investment.heading.name,
+      price(investment),
+      investment.valuation_finished? ? I18n.t('shared.yes') : I18n.t('shared.no'),
+      investment.selected? ? I18n.t('shared.yes') : I18n.t('shared.no')
+    ]
+  end
+
+  def admin(investment)
+    if investment.administrator.present?
+      investment.administrator.name
+    else
+      I18n.t("admin.budget_investments.index.no_admin_assigned")
+    end
+  end
+
+  def price(investment)
+    price_string = "admin.budget_investments.index.feasibility.#{investment.feasibility}"
+    I18n.t(price_string, price: investment.formatted_price)
+  end
+end