Add contributions CSV export

app/controllers/contributions_controller.rb

@@ -3,10 +3,24 @@ class ContributionsController < ApplicationController
   before_action :set_member, only: %i[ new create ]
   before_action :set_contribution, only: %i[ edit update delete destroy ]
 
+  def to_csv(collection, keys)
+    csv = [keys].join(",") + "\n"
+    collection.each do |item|
+      csv << keys.map { |k| item.send(k) }.join(",") + "\n"
+    end
+
+    csv
+  end
+
   # GET /contributions
   def index
     @contributions = Contribution.all.order(payment_on: 'DESC')
     @contributions = @contributions.select {|c| c.payment_on.year == params[:year].to_i } if params[:year]
+
+    respond_to do |format|
+      format.html
+      format.csv { render plain: to_csv(@contributions, %i[payment_on member_number member_display_name amount payment_method]) }
+    end
   end
 
   # GET /contributions/new

app/models/contribution.rb

@@ -1,4 +1,16 @@
 class Contribution < ApplicationRecord
   belongs_to :member
   has_paper_trail
+
+  def member_number
+    member&.number
+  end
+
+  def member_display_name
+    member&.display_name
+  end
+
+  def amount
+    eurocents
+  end
 end