Refactor organisation name changes to use integer for change_type and date for change_date

app/controllers/organisation_name_changes_controller.rb

@@ -4,7 +4,7 @@ class OrganisationNameChangesController < ApplicationController
 
   def create
     @organisation_name_change = @organisation.organisation_name_changes.new(organisation_name_change_params)
-    @organisation_name_change.change_type = "User change"
+    @organisation_name_change.change_type = :user_change
 
     if @organisation_name_change.save
       notice_message = @organisation_name_change.immediate_change ? "Name change saved successfully." : "Name change scheduled for #{@organisation_name_change.formatted_change_date}."

app/models/organisation_name_change.rb

@@ -13,6 +13,13 @@ class OrganisationNameChange < ApplicationRecord
 
   before_validation :set_change_date_if_immediate
 
+  CHANGE_TYPE = {
+    user_change: 1,
+    merge: 2,
+  }.freeze
+
+  enum :change_type, CHANGE_TYPE, prefix: true
+
   has_paper_trail
 
   def includes_date?(date)
@@ -46,7 +53,7 @@ class OrganisationNameChange < ApplicationRecord
 private
 
   def set_change_date_if_immediate
-    self.change_date = Time.zone.now if immediate_change == true
+    self.change_date = Time.zone.now if immediate_change
   end
 
   def change_date_must_be_after_last_change_date
@@ -66,8 +73,8 @@ private
   def change_date_must_be_unique_for_organisation
     return if change_date.blank?
 
-    if organisation.organisation_name_changes.visible.select(&:persisted?).any? { |record| record.change_date.to_date == change_date.to_date }
-      errors.add(:change_date, "Start date cannot be the same as a previous change date for this organisation.")
+    if organisation.organisation_name_changes.visible.select(&:persisted?).any? { |record| record.change_date == change_date }
+      errors.add(:change_date, "Start date cannot be the same as an existing name change.")
     end
   end
 

db/migrate/20250409113321_create_organisation_name_changes.rb

@@ -3,8 +3,8 @@ class CreateOrganisationNameChanges < ActiveRecord::Migration[7.2]
     create_table :organisation_name_changes do |t|
       t.references :organisation, null: false, foreign_key: true
       t.string :name, null: false
-      t.string :change_type
-      t.datetime :change_date, null: false
+      t.integer :change_type, null: false
+      t.date :change_date, null: false
       t.datetime :discarded_at
 
       t.timestamps

db/schema.rb

@@ -500,8 +500,8 @@ ActiveRecord::Schema[7.2].define(version: 2025_03_05_092900) do
   create_table "organisation_name_changes", force: :cascade do |t|
     t.bigint "organisation_id", null: false
     t.string "name", null: false
-    t.string "change_type"
-    t.datetime "change_date", null: false
+    t.integer "change_type", null: false
+    t.date "change_date", null: false
     t.datetime "discarded_at"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false