implement frecency

app/controllers/orders_controller.rb

@@ -26,7 +26,7 @@ class OrdersController < ApplicationController
   end
 
   def overview
-    @users = User.members.publik.order(:name)
+    @users = User.members.publik.order(:frecency, :desc)
     @last = Order.order(:created_at).reverse_order.includes(:user).limit(10).map(&:user)
   end
 

app/models/order.rb

@@ -21,6 +21,9 @@ class Order < ActiveRecord::Base
   before_save { |o| o.order_items = o.order_items.reject{ |oi| oi.count == 0 } }
   after_create :create_api_job, unless: -> { user.guest? }
 
+  after_create :update_user_frecency
+  after_destroy :update_user_frecency
+
   validates :user, presence: true
   validates_associated :order_items
   validate :product_presence
@@ -66,4 +69,8 @@ class Order < ActiveRecord::Base
     def product_presence
       errors.add(:base, "You have to order at least one product.") if order_items.map(&:count).sum.zero?
     end
+
+    def update_user_frecency
+      self.user.calculate_frecency
+    end
 end

app/models/user.rb

@@ -41,6 +41,14 @@ class User < ActiveRecord::Base
     end
   end
 
+  def calculate_frecency
+    num_orders = Rails.application.config.frecency_num_orders
+    last_timestamps = self.orders.order(created_at: :desc)
+                                 .limit(num_orders)
+                                 .pluck(:created_at)
+    self.frecency = last_timestamps.map(&:to_i).sum / num_orders
+  end
+
   def balance
     @balance || begin
       headers = {

config/application.rb

@@ -22,5 +22,6 @@ module Tab002
     config.active_record.raise_in_transactional_callbacks = true
     config.active_job.queue_adapter = :delayed_job
     config.call_api_after = 5.minutes
+    config.frecency_num_orders = 10
   end
 end

db/migrate/20160216133104_add_frecency_to_users.rb

@@ -0,0 +1,5 @@
+class AddFrecencyToUsers < ActiveRecord::Migration
+  def change
+    add_column :users, :frecency, :integer, default: 0, null: false
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20160202133903) do
+ActiveRecord::Schema.define(version: 20160216133104) do
 
   create_table "barcodes", force: :cascade do |t|
     t.integer  "product_id"
@@ -85,6 +85,7 @@ ActiveRecord::Schema.define(version: 20160202133903) do
     t.boolean  "koelkast",            default: false
     t.string   "name"
     t.boolean  "private",             default: false
+    t.integer  "frecency",            default: 0,     null: false
   end
 
   add_index "users", ["koelkast"], name: "index_users_on_koelkast"