Add concerns to set and order by a random seed

app/controllers/concerns/random_seed.rb

@@ -0,0 +1,10 @@
+module RandomSeed
+  extend ActiveSupport::Concern
+
+  def set_random_seed
+    seed = (params[:random_seed] || session[:random_seed] || rand(10_000_000)).to_i
+
+    session[:random_seed] = seed
+    params[:random_seed] = seed
+  end
+end

app/controllers/legislation/processes_controller.rb

@@ -1,4 +1,6 @@
 class Legislation::ProcessesController < Legislation::BaseController
+  include RandomSeed
+
   has_filters %w[open past], only: :index
   has_filters %w[random winners], only: :proposals
 
@@ -128,11 +130,4 @@ class Legislation::ProcessesController < Legislation::BaseController
       return if member_method?
       @process = ::Legislation::Process.find(params[:process_id])
     end
-
-    def set_random_seed
-      seed = (params[:random_seed] || session[:random_seed] || rand(10_000_000)).to_i
-
-      session[:random_seed] = seed
-      params[:random_seed] = seed
-    end
 end

app/models/concerns/randomizable.rb

@@ -0,0 +1,18 @@
+module Randomizable
+  extend ActiveSupport::Concern
+
+  class_methods do
+    def sort_by_random(seed)
+      ids = pluck(:id).shuffle(random: Random.new(seed))
+
+      return all if ids.empty?
+
+      ids_with_order = ids.map.with_index { |id, order| "(#{id}, #{order})" }.join(", ")
+
+      joins("LEFT JOIN (VALUES #{ids_with_order}) AS ids(id, ordering) ON #{table_name}.id = ids.id")
+        .order("ids.ordering")
+    end
+
+    alias_method :random, :sort_by_random
+  end
+end

app/models/legislation/proposal.rb

@@ -12,6 +12,7 @@ class Legislation::Proposal < ActiveRecord::Base
   include Documentable
   include Notifiable
   include Imageable
+  include Randomizable
 
   documentable max_documents_allowed: 3,
                max_file_size: 3.megabytes,
@@ -51,20 +52,8 @@ class Legislation::Proposal < ActiveRecord::Base
   scope :sort_by_flags,            -> { order(flags_count: :desc, updated_at: :desc) }
   scope :last_week,                -> { where("proposals.created_at >= ?", 7.days.ago)}
   scope :selected,                 -> { where(selected: true) }
-  scope :random,                   -> (seed) { sort_by_random(seed) }
   scope :winners,                  -> { selected.sort_by_confidence_score }
 
-  def self.sort_by_random(seed)
-    ids = pluck(:id).shuffle(random: Random.new(seed))
-
-    return all if ids.empty?
-
-    ids_with_order = ids.map.with_index { |id, order| "(#{id}, #{order})" }.join(", ")
-
-    joins("LEFT JOIN (VALUES #{ids_with_order}) AS ids(id, ordering) ON #{table_name}.id = ids.id")
-      .order("ids.ordering")
-  end
-
   def to_param
     "#{id}-#{title}".parameterize
   end